Check if the incoming interface is available and NFT_BREAK
in case neither skb->sk nor input device are set.

Because nf_sk_lookup_slow*() assume packet headers are in the
'in' direction, use in postrouting is not going to yield a meaningful
result.  Same is true for the forward chain, so restrict the use
to prerouting, input and output.

Use in output work if a socket is already attached to the skb.

Fixes: 554ced0a ("netfilter: nf_tables: add support for native socket matching")
Reported-and-tested-by: Topi Miettinen <toiwoton@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

`nf_flowtable_udp_timeout` sysctl option is available only
if CONFIG_NFT_FLOW_OFFLOAD enabled. But infra for this flow
offload UDP timeout was added under CONFIG_NF_FLOW_TABLE
config option. So, if you have CONFIG_NFT_FLOW_OFFLOAD
disabled and CONFIG_NF_FLOW_TABLE enabled, the
`nf_flowtable_udp_timeout` is not present in sysfs.
Please note, that TCP flow offload timeout sysctl option
is present even CONFIG_NFT_FLOW_OFFLOAD is disabled.

I suppose it was a typo in commit that adds UDP flow offload
timeout and CONFIG_NF_FLOW_TABLE should be used instead.

Fixes: 975c5750 ("netfilter: conntrack: Introduce udp offload timeout configuration")
Signed-off-by: Volodymyr Mytnyk <volodymyr.mytnyk@plvision.eu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

Jaco Kroon reported tcp problems that Eric Dumazet and Neal Cardwell
pinpointed to nf_conntrack tcp_in_window() bug.

tcp trace shows following sequence:

I > R Flags [S], seq 3451342529, win 62580, options [.. tfo [|tcp]>
R > I Flags [S.], seq 2699962254, ack 3451342530, win 65535, options [..]
R > I Flags [P.], seq 1:89, ack 1, [..]

Note 3rd ACK is from responder to initiator so following branch is taken:
    } else if (((state->state == TCP_CONNTRACK_SYN_SENT
               && dir == IP_CT_DIR_ORIGINAL)
               || (state->state == TCP_CONNTRACK_SYN_RECV
               && dir == IP_CT_DIR_REPLY))
               && after(end, sender->td_end)) {

... because state == TCP_CONNTRACK_SYN_RECV and dir is REPLY.
This causes the scaling factor to be reset to 0: window scale option
is only present in syn(ack) packets.  This in turn makes nf_conntrack
mark valid packets as out-of-window.

This was always broken, it exists even in original commit where
window tracking was added to ip_conntrack (nf_conntrack predecessor)
in 2.6.9-rc1 kernel.

Restrict to 'tcph->syn', just like the 3rd condtional added in
commit 82b72cb9 ("netfilter: conntrack: re-init state for retransmitted syn-ack").

Upon closer look, those conditionals/branches can be merged:

Because earlier checks prevent syn-ack from showing up in
original direction, the 'dir' checks in the conditional quoted above are
redundant, remove them. Return early for pure syn retransmitted in reply
direction (simultaneous open).

Fixes: 9fb9cbb1 ("[NETFILTER]: Add nf_conntrack subsystem.")
Reported-by: Jaco Kroon <jaco@uls.co.za>
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Jozsef Kadlecsik <kadlec@netfilter.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

-queue

Tony Nguyen says:

====================
Intel Wired LAN Driver Updates 2022-04-26

This series contains updates to ice driver only.

Ivan Vecera removes races related to VF message processing by changing
mutex_trylock() call to mutex_lock() and moving additional operations
to occur under mutex.

Petr Oros increases wait time after firmware flash as current time is
not sufficient.

Jake resolves a use-after-free issue for mailbox snapshot.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Commit 4b592324 ("net: dsa: lantiq_gswip: Configure all remaining
GSWIP_MII_CFG bits") added all known bits in the GSWIP_MII_CFGp
register. It helped bring this register into a well-defined state so the
driver has to rely less on the bootloader to do things right.
Unfortunately it also sets the GSWIP_MII_CFG_RMII_CLK bit without any
possibility to configure it. Upon further testing it turns out that all
boards which are supported by the GSWIP driver in OpenWrt which use an
RMII PHY have a dedicated oscillator on the board which provides the
50MHz RMII reference clock.

Don't set the GSWIP_MII_CFG_RMII_CLK bit (but keep the code which always
clears it) to fix support for the Fritz!Box 7362 SL in OpenWrt. This is
a board with two Atheros AR8030 RMII PHYs. With the "RMII clock" bit set
the MAC also generates the RMII reference clock whose signal then
conflicts with the signal from the oscillator on the board. This results
in a constant cycle of the PHY detecting link up/down (and as a result
of that: the two ports using the AR8030 PHYs are not working).

At the time of writing this patch there's no known board where the MAC
(GSWIP) has to generate the RMII reference clock. If needed this can be
implemented in future by providing a device-tree flag so the
GSWIP_MII_CFG_RMII_CLK bit can be toggled per port.

Fixes: 4b592324 ("net: dsa: lantiq_gswip: Configure all remaining GSWIP_MII_CFG bits")
Tested-by: Jan Hoffmann <jan@3e8.eu>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Acked-by: Hauke Mehrtens <hauke@hauke-m.de>
Link: https://lore.kernel.org/r/20220425152027.2220750-1-martin.blumenstingl@googlemail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

The macro dev_core_stats_##FIELD##_inc() disables preemption and invokes
netdev_core_stats_alloc() to return a per-CPU pointer.
netdev_core_stats_alloc() will allocate memory on its first invocation
which breaks on PREEMPT_RT because it requires non-atomic context for
memory allocation.

This can be avoided by enabling preemption in netdev_core_stats_alloc()
assuming the caller always disables preemption.

It might be better to replace local_inc() with this_cpu_inc() now that
dev_core_stats_##FIELD##_inc() gained a preempt-disable section and does
not rely on already disabled preemption. This results in less
instructions on x86-64:
local_inc:
|          incl %gs:__preempt_count(%rip)  # __preempt_count
|          movq    488(%rdi), %rax # _1->core_stats, _22
|          testq   %rax, %rax      # _22
|          je      .L585   #,
|          add %gs:this_cpu_off(%rip), %rax        # this_cpu_off, tcp_ptr__
|  .L586:
|          testq   %rax, %rax      # _27
|          je      .L587   #,
|          incq (%rax)            # _6->a.counter
|  .L587:
|          decl %gs:__preempt_count(%rip)  # __preempt_count

this_cpu_inc(), this patch:
|         movq    488(%rdi), %rax # _1->core_stats, _5
|         testq   %rax, %rax      # _5
|         je      .L591   #,
| .L585:
|         incq %gs:(%rax) # _18->rx_dropped

Use unsigned long as type for the counter. Use this_cpu_inc() to
increment the counter. Use a plain read of the counter.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/YmbO0pxgtKpCw4SY@linutronix.deSigned-off-by: Jakub Kicinski <kuba@kernel.org>

During ice_sriov_configure, if num_vfs is 0, we are being asked by the
kernel to remove all VFs.

The driver first de-initializes the snapshot before freeing all the VFs.
This results in a use-after-free BUG detected by KASAN. The bug occurs
because the snapshot can still be accessed until all VFs are removed.

Fix this by freeing all the VFs first before calling
ice_mbx_deinit_snapshot.

[  +0.032591] ==================================================================
[  +0.000021] BUG: KASAN: use-after-free in ice_mbx_vf_state_handler+0x1c3/0x410 [ice]
[  +0.000315] Write of size 28 at addr ffff889908eb6f28 by task kworker/55:2/1530996

[  +0.000029] CPU: 55 PID: 1530996 Comm: kworker/55:2 Kdump: loaded Tainted: G S        I       5.17.0-dirty #1
[  +0.000022] Hardware name: Dell Inc. PowerEdge R740/0923K0, BIOS 1.6.13 12/17/2018
[  +0.000013] Workqueue: ice ice_service_task [ice]
[  +0.000279] Call Trace:
[  +0.000012]  <TASK>
[  +0.000011]  dump_stack_lvl+0x33/0x42
[  +0.000030]  print_report.cold.13+0xb2/0x6b3
[  +0.000028]  ? ice_mbx_vf_state_handler+0x1c3/0x410 [ice]
[  +0.000295]  kasan_report+0xa5/0x120
[  +0.000026]  ? __switch_to_asm+0x21/0x70
[  +0.000024]  ? ice_mbx_vf_state_handler+0x1c3/0x410 [ice]
[  +0.000298]  kasan_check_range+0x183/0x1e0
[  +0.000019]  memset+0x1f/0x40
[  +0.000018]  ice_mbx_vf_state_handler+0x1c3/0x410 [ice]
[  +0.000304]  ? ice_conv_link_speed_to_virtchnl+0x160/0x160 [ice]
[  +0.000297]  ? ice_vsi_dis_spoofchk+0x40/0x40 [ice]
[  +0.000305]  ice_is_malicious_vf+0x1aa/0x250 [ice]
[  +0.000303]  ? ice_restore_all_vfs_msi_state+0x160/0x160 [ice]
[  +0.000297]  ? __mutex_unlock_slowpath.isra.15+0x410/0x410
[  +0.000022]  ? ice_debug_cq+0xb7/0x230 [ice]
[  +0.000273]  ? __kasan_slab_alloc+0x2f/0x90
[  +0.000022]  ? memset+0x1f/0x40
[  +0.000017]  ? do_raw_spin_lock+0x119/0x1d0
[  +0.000022]  ? rwlock_bug.part.2+0x60/0x60
[  +0.000024]  __ice_clean_ctrlq+0x3a6/0xd60 [ice]
[  +0.000273]  ? newidle_balance+0x5b1/0x700
[  +0.000026]  ? ice_print_link_msg+0x2f0/0x2f0 [ice]
[  +0.000271]  ? update_cfs_group+0x1b/0x140
[  +0.000018]  ? load_balance+0x1260/0x1260
[  +0.000022]  ? ice_process_vflr_event+0x27/0x130 [ice]
[  +0.000301]  ice_service_task+0x136e/0x1470 [ice]
[  +0.000281]  process_one_work+0x3b4/0x6c0
[  +0.000030]  worker_thread+0x65/0x660
[  +0.000023]  ? __kthread_parkme+0xe4/0x100
[  +0.000021]  ? process_one_work+0x6c0/0x6c0
[  +0.000020]  kthread+0x179/0x1b0
[  +0.000018]  ? kthread_complete_and_exit+0x20/0x20
[  +0.000022]  ret_from_fork+0x22/0x30
[  +0.000026]  </TASK>

[  +0.000018] Allocated by task 10742:
[  +0.000013]  kasan_save_stack+0x1c/0x40
[  +0.000018]  __kasan_kmalloc+0x84/0xa0
[  +0.000016]  kmem_cache_alloc_trace+0x16c/0x2e0
[  +0.000015]  intel_iommu_probe_device+0xeb/0x860
[  +0.000015]  __iommu_probe_device+0x9a/0x2f0
[  +0.000016]  iommu_probe_device+0x43/0x270
[  +0.000015]  iommu_bus_notifier+0xa7/0xd0
[  +0.000015]  blocking_notifier_call_chain+0x90/0xc0
[  +0.000017]  device_add+0x5f3/0xd70
[  +0.000014]  pci_device_add+0x404/0xa40
[  +0.000015]  pci_iov_add_virtfn+0x3b0/0x550
[  +0.000016]  sriov_enable+0x3bb/0x600
[  +0.000013]  ice_ena_vfs+0x113/0xa79 [ice]
[  +0.000293]  ice_sriov_configure.cold.17+0x21/0xe0 [ice]
[  +0.000291]  sriov_numvfs_store+0x160/0x200
[  +0.000015]  kernfs_fop_write_iter+0x1db/0x270
[  +0.000018]  new_sync_write+0x21d/0x330
[  +0.000013]  vfs_write+0x376/0x410
[  +0.000013]  ksys_write+0xba/0x150
[  +0.000012]  do_syscall_64+0x3a/0x80
[  +0.000012]  entry_SYSCALL_64_after_hwframe+0x44/0xae

[  +0.000028] Freed by task 10742:
[  +0.000011]  kasan_save_stack+0x1c/0x40
[  +0.000015]  kasan_set_track+0x21/0x30
[  +0.000016]  kasan_set_free_info+0x20/0x30
[  +0.000012]  __kasan_slab_free+0x104/0x170
[  +0.000016]  kfree+0x9b/0x470
[  +0.000013]  devres_destroy+0x1c/0x20
[  +0.000015]  devm_kfree+0x33/0x40
[  +0.000012]  ice_mbx_deinit_snapshot+0x39/0x70 [ice]
[  +0.000295]  ice_sriov_configure+0xb0/0x260 [ice]
[  +0.000295]  sriov_numvfs_store+0x1bc/0x200
[  +0.000015]  kernfs_fop_write_iter+0x1db/0x270
[  +0.000016]  new_sync_write+0x21d/0x330
[  +0.000012]  vfs_write+0x376/0x410
[  +0.000012]  ksys_write+0xba/0x150
[  +0.000012]  do_syscall_64+0x3a/0x80
[  +0.000012]  entry_SYSCALL_64_after_hwframe+0x44/0xae

[  +0.000024] Last potentially related work creation:
[  +0.000010]  kasan_save_stack+0x1c/0x40
[  +0.000016]  __kasan_record_aux_stack+0x98/0xa0
[  +0.000013]  insert_work+0x34/0x160
[  +0.000015]  __queue_work+0x20e/0x650
[  +0.000016]  queue_work_on+0x4c/0x60
[  +0.000015]  nf_nat_masq_schedule+0x297/0x2e0 [nf_nat]
[  +0.000034]  masq_device_event+0x5a/0x60 [nf_nat]
[  +0.000031]  raw_notifier_call_chain+0x5f/0x80
[  +0.000017]  dev_close_many+0x1d6/0x2c0
[  +0.000015]  unregister_netdevice_many+0x4e3/0xa30
[  +0.000015]  unregister_netdevice_queue+0x192/0x1d0
[  +0.000014]  iavf_remove+0x8f9/0x930 [iavf]
[  +0.000058]  pci_device_remove+0x65/0x110
[  +0.000015]  device_release_driver_internal+0xf8/0x190
[  +0.000017]  pci_stop_bus_device+0xb5/0xf0
[  +0.000014]  pci_stop_and_remove_bus_device+0xe/0x20
[  +0.000016]  pci_iov_remove_virtfn+0x19c/0x230
[  +0.000015]  sriov_disable+0x4f/0x170
[  +0.000014]  ice_free_vfs+0x9a/0x490 [ice]
[  +0.000306]  ice_sriov_configure+0xb8/0x260 [ice]
[  +0.000294]  sriov_numvfs_store+0x1bc/0x200
[  +0.000015]  kernfs_fop_write_iter+0x1db/0x270
[  +0.000016]  new_sync_write+0x21d/0x330
[  +0.000012]  vfs_write+0x376/0x410
[  +0.000012]  ksys_write+0xba/0x150
[  +0.000012]  do_syscall_64+0x3a/0x80
[  +0.000012]  entry_SYSCALL_64_after_hwframe+0x44/0xae

[  +0.000025] The buggy address belongs to the object at ffff889908eb6f00
               which belongs to the cache kmalloc-96 of size 96
[  +0.000016] The buggy address is located 40 bytes inside of
               96-byte region [ffff889908eb6f00, ffff889908eb6f60)

[  +0.000026] The buggy address belongs to the physical page:
[  +0.000010] page:00000000b7e99a2e refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1908eb6
[  +0.000016] flags: 0x57ffffc0000200(slab|node=1|zone=2|lastcpupid=0x1fffff)
[  +0.000024] raw: 0057ffffc0000200 ffffea0069d9fd80 dead000000000002 ffff88810004c780
[  +0.000015] raw: 0000000000000000 0000000000200020 00000001ffffffff 0000000000000000
[  +0.000009] page dumped because: kasan: bad access detected

[  +0.000016] Memory state around the buggy address:
[  +0.000012]  ffff889908eb6e00: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
[  +0.000014]  ffff889908eb6e80: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
[  +0.000014] >ffff889908eb6f00: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
[  +0.000011]                                   ^
[  +0.000013]  ffff889908eb6f80: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
[  +0.000013]  ffff889908eb7000: fa fb fb fb fb fb fb fb fc fc fc fc fa fb fb fb
[  +0.000012] ==================================================================

Fixes: 0891c896 ("ice: warn about potentially malicious VFs")
Reported-by: Slawomir Laba <slawomirx.laba@intel.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Konrad Jankowski <konrad0.jankowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

We need to wait 5 s for EMP reset after firmware flash. Code was extracted
from OOT driver (ice v1.8.3 downloaded from sourceforge). Without this
wait, fw_activate let card in inconsistent state and recoverable only
by second flash/activate. Flash was tested on these fw's:
From -> To
 3.00 -> 3.10/3.20
 3.10 -> 3.00/3.20
 3.20 -> 3.00/3.10

Reproducer:
[root@host ~]# devlink dev flash pci/0000:ca:00.0 file E810_XXVDA4_FH_O_SEC_FW_1p6p1p9_NVM_3p10_PLDMoMCTP_0.11_8000AD7B.bin
Preparing to flash
[fw.mgmt] Erasing
[fw.mgmt] Erasing done
[fw.mgmt] Flashing 100%
[fw.mgmt] Flashing done 100%
[fw.undi] Erasing
[fw.undi] Erasing done
[fw.undi] Flashing 100%
[fw.undi] Flashing done 100%
[fw.netlist] Erasing
[fw.netlist] Erasing done
[fw.netlist] Flashing 100%
[fw.netlist] Flashing done 100%
Activate new firmware by devlink reload
[root@host ~]# devlink dev reload pci/0000:ca:00.0 action fw_activate
reload_actions_performed:
    fw_activate
[root@host ~]# ip link show ens7f0
71: ens7f0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN mode DEFAULT group default qlen 1000
    link/ether b4:96:91:dc:72:e0 brd ff:ff:ff:ff:ff:ff
    altname enp202s0f0

dmesg after flash:
[   55.120788] ice: Copyright (c) 2018, Intel Corporation.
[   55.274734] ice 0000:ca:00.0: Get PHY capabilities failed status = -5, continuing anyway
[   55.569797] ice 0000:ca:00.0: The DDP package was successfully loaded: ICE OS Default Package version 1.3.28.0
[   55.603629] ice 0000:ca:00.0: Get PHY capability failed.
[   55.608951] ice 0000:ca:00.0: ice_init_nvm_phy_type failed: -5
[   55.647348] ice 0000:ca:00.0: PTP init successful
[   55.675536] ice 0000:ca:00.0: DCB is enabled in the hardware, max number of TCs supported on this port are 8
[   55.685365] ice 0000:ca:00.0: FW LLDP is disabled, DCBx/LLDP in SW mode.
[   55.692179] ice 0000:ca:00.0: Commit DCB Configuration to the hardware
[   55.701382] ice 0000:ca:00.0: 126.024 Gb/s available PCIe bandwidth, limited by 16.0 GT/s PCIe x8 link at 0000:c9:02.0 (capable of 252.048 Gb/s with 16.0 GT/s PCIe x16 link)
Reboot doesn’t help, only second flash/activate with OOT or patched
driver put card back in consistent state.

After patch:
[root@host ~]# devlink dev flash pci/0000:ca:00.0 file E810_XXVDA4_FH_O_SEC_FW_1p6p1p9_NVM_3p10_PLDMoMCTP_0.11_8000AD7B.bin
Preparing to flash
[fw.mgmt] Erasing
[fw.mgmt] Erasing done
[fw.mgmt] Flashing 100%
[fw.mgmt] Flashing done 100%
[fw.undi] Erasing
[fw.undi] Erasing done
[fw.undi] Flashing 100%
[fw.undi] Flashing done 100%
[fw.netlist] Erasing
[fw.netlist] Erasing done
[fw.netlist] Flashing 100%
[fw.netlist] Flashing done 100%
Activate new firmware by devlink reload
[root@host ~]# devlink dev reload pci/0000:ca:00.0 action fw_activate
reload_actions_performed:
    fw_activate
[root@host ~]# ip link show ens7f0
19: ens7f0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode DEFAULT group default qlen 1000
    link/ether b4:96:91:dc:72:e0 brd ff:ff:ff:ff:ff:ff
    altname enp202s0f0

Fixes: 399e27db ("ice: support immediate firmware activation via devlink reload")
Signed-off-by: Petr Oros <poros@redhat.com>
Tested-by: Gurucharan <gurucharanx.g@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

Previous patch labelled "ice: Fix incorrect locking in
ice_vc_process_vf_msg()"  fixed an issue with ignored messages
sent by VF driver but a small race window still left.

Recently caught trace during 'ip link set ... vf 0 vlan ...' operation:

[ 7332.995625] ice 0000:3b:00.0: Clearing port VLAN on VF 0
[ 7333.001023] iavf 0000:3b:01.0: Reset indication received from the PF
[ 7333.007391] iavf 0000:3b:01.0: Scheduling reset task
[ 7333.059575] iavf 0000:3b:01.0: PF returned error -5 (IAVF_ERR_PARAM) to our request 3
[ 7333.059626] ice 0000:3b:00.0: Invalid message from VF 0, opcode 3, len 4, error -1

Setting of VLAN for VF causes a reset of the affected VF using
ice_reset_vf() function that runs with cfg_lock taken:

1. ice_notify_vf_reset() informs IAVF driver that reset is needed and
   IAVF schedules its own reset procedure
2. Bit ICE_VF_STATE_DIS is set in vf->vf_state
3. Misc initialization steps
4. ice_sriov_post_vsi_rebuild() -> ice_vf_set_initialized() and that
   clears ICE_VF_STATE_DIS in vf->vf_state

Step 3 is mentioned race window because IAVF reset procedure runs in
parallel and one of its step is sending of VIRTCHNL_OP_GET_VF_RESOURCES
message (opcode==3). This message is handled in ice_vc_process_vf_msg()
and if it is received during the mentioned race window then it's
marked as invalid and error is returned to VF driver.

Protect vf_state check in ice_vc_process_vf_msg() by cfg_lock to avoid
this race condition.

Fixes: e6ba5273 ("ice: Fix race conditions between virtchnl handling and VF ndo ops")
Tested-by: Fei Liu <feliu@redhat.com>
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Konrad Jankowski <konrad0.jankowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

Usage of mutex_trylock() in ice_vc_process_vf_msg() is incorrect
because message sent from VF is ignored and never processed.

Use mutex_lock() instead to fix the issue. It is safe because this
mutex is used to prevent races between VF related NDOs and
handlers processing request messages from VF and these handlers
are running in ice_service_task() context. Additionally move this
mutex lock prior ice_vc_is_opcode_allowed() call to avoid potential
races during allowlist access.

Fixes: e6ba5273 ("ice: Fix race conditions between virtchnl handling and VF ndo ops")
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Tested-by: Konrad Jankowski <konrad0.jankowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

We received a report[1] of kernel crashes when Cilium is used in XDP
mode with virtio_net after updating to newer kernels. After
investigating the reason it turned out that when using mergeable bufs
with an XDP program which adjusts xdp.data or xdp.data_meta page_to_buf()
calculates the build_skb address wrong because the offset can become less
than the headroom so it gets the address of the previous page (-X bytes
depending on how lower offset is):
 page_to_skb: page addr ffff9eb2923e2000 buf ffff9eb2923e1ffc offset 252 headroom 256

This is a pr_err() I added in the beginning of page_to_skb which clearly
shows offset that is less than headroom by adding 4 bytes of metadata
via an xdp prog. The calculations done are:
 receive_mergeable():
 headroom = VIRTIO_XDP_HEADROOM; // VIRTIO_XDP_HEADROOM == 256 bytes
 offset = xdp.data - page_address(xdp_page) -
          vi->hdr_len - metasize;

 page_to_skb():
 p = page_address(page) + offset;
 ...
 buf = p - headroom;

Now buf goes -4 bytes from the page's starting address as can be seen
above which is set as skb->head and skb->data by build_skb later. Depending
on what's done with the skb (when it's freed most often) we get all kinds
of corruptions and BUG_ON() triggers in mm[2]. We have to recalculate
the new headroom after the xdp program has run, similar to how offset
and len are recalculated. Headroom is directly related to
data_hard_start, data and data_meta, so we use them to get the new size.
The result is correct (similar pr_err() in page_to_skb, one case of
xdp_page and one case of virtnet buf):
 a) Case with 4 bytes of metadata
 [  115.949641] page_to_skb: page addr ffff8b4dcfad2000 offset 252 headroom 252
 [  121.084105] page_to_skb: page addr ffff8b4dcf018000 offset 20732 headroom 252
 b) Case of pushing data +32 bytes
 [  153.181401] page_to_skb: page addr ffff8b4dd0c4d000 offset 288 headroom 288
 [  158.480421] page_to_skb: page addr ffff8b4dd00b0000 offset 24864 headroom 288
 c) Case of pushing data -33 bytes
 [  835.906830] page_to_skb: page addr ffff8b4dd3270000 offset 223 headroom 223
 [  840.839910] page_to_skb: page addr ffff8b4dcdd68000 offset 12511 headroom 223

Offset and headroom are equal because offset points to the start of
reserved bytes for the virtio_net header which are at buf start +
headroom, while data points at buf start + vnet hdr size + headroom so
when data or data_meta are adjusted by the xdp prog both the headroom size
and the offset change equally. We can use data_hard_start to compute the
new headroom after the xdp prog (linearized / page start case, the
virtnet buf case is similar just with bigger base offset):
 xdp.data_hard_start = page_address + vnet_hdr
 xdp.data = page_address + vnet_hdr + headroom
 new headroom after xdp prog = xdp.data - xdp.data_hard_start - metasize

An example reproducer xdp prog[3] is below.

[1] https://github.com/cilium/cilium/issues/19453

[2] Two of the many traces:
 [   40.437400] BUG: Bad page state in process swapper/0  pfn:14940
 [   40.916726] BUG: Bad page state in process systemd-resolve  pfn:053b7
 [   41.300891] kernel BUG at include/linux/mm.h:720!
 [   41.301801] invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
 [   41.302784] CPU: 1 PID: 1181 Comm: kubelet Kdump: loaded Tainted: G    B   W         5.18.0-rc1+ #37
 [   41.304458] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1.fc35 04/01/2014
 [   41.306018] RIP: 0010:page_frag_free+0x79/0xe0
 [   41.306836] Code: 00 00 75 ea 48 8b 07 a9 00 00 01 00 74 e0 48 8b 47 48 48 8d 50 ff a8 01 48 0f 45 fa eb d0 48 c7 c6 18 b8 30 a6 e8 d7 f8 fc ff <0f> 0b 48 8d 78 ff eb bc 48 8b 07 a9 00 00 01 00 74 3a 66 90 0f b6
 [   41.310235] RSP: 0018:ffffac05c2a6bc78 EFLAGS: 00010292
 [   41.311201] RAX: 000000000000003e RBX: 0000000000000000 RCX: 0000000000000000
 [   41.312502] RDX: 0000000000000001 RSI: ffffffffa6423004 RDI: 00000000ffffffff
 [   41.313794] RBP: ffff993c98823600 R08: 0000000000000000 R09: 00000000ffffdfff
 [   41.315089] R10: ffffac05c2a6ba68 R11: ffffffffa698ca28 R12: ffff993c98823600
 [   41.316398] R13: ffff993c86311ebc R14: 0000000000000000 R15: 000000000000005c
 [   41.317700] FS:  00007fe13fc56740(0000) GS:ffff993cdd900000(0000) knlGS:0000000000000000
 [   41.319150] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 [   41.320152] CR2: 000000c00008a000 CR3: 0000000014908000 CR4: 0000000000350ee0
 [   41.321387] Call Trace:
 [   41.321819]  <TASK>
 [   41.322193]  skb_release_data+0x13f/0x1c0
 [   41.322902]  __kfree_skb+0x20/0x30
 [   41.343870]  tcp_recvmsg_locked+0x671/0x880
 [   41.363764]  tcp_recvmsg+0x5e/0x1c0
 [   41.384102]  inet_recvmsg+0x42/0x100
 [   41.406783]  ? sock_recvmsg+0x1d/0x70
 [   41.428201]  sock_read_iter+0x84/0xd0
 [   41.445592]  ? 0xffffffffa3000000
 [   41.462442]  new_sync_read+0x148/0x160
 [   41.479314]  ? 0xffffffffa3000000
 [   41.496937]  vfs_read+0x138/0x190
 [   41.517198]  ksys_read+0x87/0xc0
 [   41.535336]  do_syscall_64+0x3b/0x90
 [   41.551637]  entry_SYSCALL_64_after_hwframe+0x44/0xae
 [   41.568050] RIP: 0033:0x48765b
 [   41.583955] Code: e8 4a 35 fe ff eb 88 cc cc cc cc cc cc cc cc e8 fb 7a fe ff 48 8b 7c 24 10 48 8b 74 24 18 48 8b 54 24 20 48 8b 44 24 08 0f 05 <48> 3d 01 f0 ff ff 76 20 48 c7 44 24 28 ff ff ff ff 48 c7 44 24 30
 [   41.632818] RSP: 002b:000000c000a2f5b8 EFLAGS: 00000212 ORIG_RAX: 0000000000000000
 [   41.664588] RAX: ffffffffffffffda RBX: 000000c000062000 RCX: 000000000048765b
 [   41.681205] RDX: 0000000000005e54 RSI: 000000c000e66000 RDI: 0000000000000016
 [   41.697164] RBP: 000000c000a2f608 R08: 0000000000000001 R09: 00000000000001b4
 [   41.713034] R10: 00000000000000b6 R11: 0000000000000212 R12: 00000000000000e9
 [   41.728755] R13: 0000000000000001 R14: 000000c000a92000 R15: ffffffffffffffff
 [   41.744254]  </TASK>
 [   41.758585] Modules linked in: br_netfilter bridge veth netconsole virtio_net

 and

 [   33.524802] BUG: Bad page state in process systemd-network  pfn:11e60
 [   33.528617] page ffffe05dc0147b00 ffffe05dc04e7a00 ffff8ae9851ec000 (1) len 82 offset 252 metasize 4 hroom 0 hdr_len 12 data ffff8ae9851ec10c data_meta ffff8ae9851ec108 data_end ffff8ae9851ec14e
 [   33.529764] page:000000003792b5ba refcount:0 mapcount:-512 mapping:0000000000000000 index:0x0 pfn:0x11e60
 [   33.532463] flags: 0xfffffc0000000(node=0|zone=1|lastcpupid=0x1fffff)
 [   33.532468] raw: 000fffffc0000000 0000000000000000 dead000000000122 0000000000000000
 [   33.532470] raw: 0000000000000000 0000000000000000 00000000fffffdff 0000000000000000
 [   33.532471] page dumped because: nonzero mapcount
 [   33.532472] Modules linked in: br_netfilter bridge veth netconsole virtio_net
 [   33.532479] CPU: 0 PID: 791 Comm: systemd-network Kdump: loaded Not tainted 5.18.0-rc1+ #37
 [   33.532482] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1.fc35 04/01/2014
 [   33.532484] Call Trace:
 [   33.532496]  <TASK>
 [   33.532500]  dump_stack_lvl+0x45/0x5a
 [   33.532506]  bad_page.cold+0x63/0x94
 [   33.532510]  free_pcp_prepare+0x290/0x420
 [   33.532515]  free_unref_page+0x1b/0x100
 [   33.532518]  skb_release_data+0x13f/0x1c0
 [   33.532524]  kfree_skb_reason+0x3e/0xc0
 [   33.532527]  ip6_mc_input+0x23c/0x2b0
 [   33.532531]  ip6_sublist_rcv_finish+0x83/0x90
 [   33.532534]  ip6_sublist_rcv+0x22b/0x2b0

[3] XDP program to reproduce(xdp_pass.c):
 #include <linux/bpf.h>
 #include <bpf/bpf_helpers.h>

 SEC("xdp_pass")
 int xdp_pkt_pass(struct xdp_md *ctx)
 {
          bpf_xdp_adjust_head(ctx, -(int)32);
          return XDP_PASS;
 }

 char _license[] SEC("license") = "GPL";

 compile: clang -O2 -g -Wall -target bpf -c xdp_pass.c -o xdp_pass.o
 load on virtio_net: ip link set enp1s0 xdpdrv obj xdp_pass.o sec xdp_pass

CC: stable@vger.kernel.org
CC: Jason Wang <jasowang@redhat.com>
CC: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
CC: Daniel Borkmann <daniel@iogearbox.net>
CC: "Michael S. Tsirkin" <mst@redhat.com>
CC: virtualization@lists.linux-foundation.org
Fixes: 8fb7da9e ("virtio_net: get build_skb() buf by data ptr")
Signed-off-by: Nikolay Aleksandrov <razor@blackwall.org>
Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20220425103703.3067292-1-razor@blackwall.orgSigned-off-by: Paolo Abeni <pabeni@redhat.com>

The other port_hidden functions rely on the port_read/port_write
functions to access the hidden control port. These functions apply the
offset for port_base_addr where applicable. Update port_hidden_wait to
use the port_wait_bit so that port_base_addr offsets are accounted for
when waiting for the busy bit to change.

Without the offset the port_hidden_wait function would timeout on
devices that have a non-zero port_base_addr (e.g. MV88E6141), however
devices that have a zero port_base_addr would operate correctly (e.g.
MV88E6390).

Fixes: 60907013 ("net: dsa: mv88e6xxx: update code operating on hidden registers")
Signed-off-by: Nathan Rossi <nathan@nathanrossi.com>
Reviewed-by: Marek Behún <kabel@kernel.org>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20220425070454.348584-1-nathan@nathanrossi.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

Return back the error value that we get from phy_read_mmd().

Fixes: c84786fa ("net: phy: marvell10g: read copper results from CSSR1")
Signed-off-by: Baruch Siach <baruch.siach@siklu.com>
Reviewed-by: Marek Behún <kabel@kernel.org>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://lore.kernel.org/r/f47cb031aeae873bb008ba35001607304a171a20.1650868058.git.baruch@tkos.co.ilSigned-off-by: Paolo Abeni <pabeni@redhat.com>

The hardware checksum offloading requires use of a transmit
status block inserted before the outgoing frame data, this was
updated in '9a9ba2a4 ("net: bcmgenet: always enable status blocks")'

However, skb_tx_timestamp() assumes that it is passed a raw frame
and PTP parsing chokes on this status block.

Fix this by calling __skb_pull(), which hides the TSB before calling
skb_tx_timestamp(), so an outgoing PTP packet is parsed correctly.

As the data in the skb has already been set up for DMA, and the
dma_unmap_* calls use a separately stored address, there is no
no effective change in the data transmission.
Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20220424165307.591145-1-jonathan.lemon@gmail.com
Fixes: d03825fb ("net: bcmgenet: add skb_tx_timestamp call")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

The function mctp_unregister() reclaims the device's relevant resource
when a netcard detaches. However, a running routine may be unaware of
this and cause the use-after-free of the mdev->addrs object.

The race condition can be demonstrated below

 cleanup thread               another thread
                          |
unregister_netdev()       |  mctp_sendmsg()
...                       |    ...
  mctp_unregister()       |    rt = mctp_route_lookup()
    ...                   |    mctl_local_output()
    kfree(mdev->addrs)    |      ...
                          |      saddr = rt->dev->addrs[0];
                          |

An attacker can adopt the (recent provided) mtcpserial driver with pty
to fake the device detaching and use the userfaultfd to increase the
race success chance (in mctp_sendmsg). The KASan report for such a POC
is shown below:

[   86.051955] ==================================================================
[   86.051955] BUG: KASAN: use-after-free in mctp_local_output+0x4e9/0xb7d
[   86.051955] Read of size 1 at addr ffff888005f298c0 by task poc/295
[   86.051955]
[   86.051955] Call Trace:
[   86.051955]  <TASK>
[   86.051955]  dump_stack_lvl+0x33/0x42
[   86.051955]  print_report.cold.13+0xb2/0x6b3
[   86.051955]  ? preempt_schedule_irq+0x57/0x80
[   86.051955]  ? mctp_local_output+0x4e9/0xb7d
[   86.051955]  kasan_report+0xa5/0x120
[   86.051955]  ? mctp_local_output+0x4e9/0xb7d
[   86.051955]  mctp_local_output+0x4e9/0xb7d
[   86.051955]  ? mctp_dev_set_key+0x79/0x79
[   86.051955]  ? copyin+0x38/0x50
[   86.051955]  ? _copy_from_iter+0x1b6/0xf20
[   86.051955]  ? sysvec_apic_timer_interrupt+0x97/0xb0
[   86.051955]  ? asm_sysvec_apic_timer_interrupt+0x12/0x20
[   86.051955]  ? mctp_local_output+0x1/0xb7d
[   86.051955]  mctp_sendmsg+0x64d/0xdb0
[   86.051955]  ? mctp_sk_close+0x20/0x20
[   86.051955]  ? __fget_light+0x2fd/0x4f0
[   86.051955]  ? mctp_sk_close+0x20/0x20
[   86.051955]  sock_sendmsg+0xdd/0x110
[   86.051955]  __sys_sendto+0x1cc/0x2a0
[   86.051955]  ? __ia32_sys_getpeername+0xa0/0xa0
[   86.051955]  ? new_sync_write+0x335/0x550
[   86.051955]  ? alloc_file+0x22f/0x500
[   86.051955]  ? __ip_do_redirect+0x820/0x1820
[   86.051955]  ? vfs_write+0x44d/0x7b0
[   86.051955]  ? vfs_write+0x44d/0x7b0
[   86.051955]  ? fput_many+0x15/0x120
[   86.051955]  ? ksys_write+0x155/0x1b0
[   86.051955]  ? __ia32_sys_read+0xa0/0xa0
[   86.051955]  __x64_sys_sendto+0xd8/0x1b0
[   86.051955]  ? exit_to_user_mode_prepare+0x2f/0x120
[   86.051955]  ? syscall_exit_to_user_mode+0x12/0x20
[   86.051955]  do_syscall_64+0x3a/0x80
[   86.051955]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   86.051955] RIP: 0033:0x7f82118a56b3
[   86.051955] RSP: 002b:00007ffdb154b110 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
[   86.051955] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f82118a56b3
[   86.051955] RDX: 0000000000000010 RSI: 00007f8211cd4000 RDI: 0000000000000007
[   86.051955] RBP: 00007ffdb154c1d0 R08: 00007ffdb154b164 R09: 000000000000000c
[   86.051955] R10: 0000000000000000 R11: 0000000000000293 R12: 000055d779800db0
[   86.051955] R13: 00007ffdb154c2b0 R14: 0000000000000000 R15: 0000000000000000
[   86.051955]  </TASK>
[   86.051955]
[   86.051955] Allocated by task 295:
[   86.051955]  kasan_save_stack+0x1c/0x40
[   86.051955]  __kasan_kmalloc+0x84/0xa0
[   86.051955]  mctp_rtm_newaddr+0x242/0x610
[   86.051955]  rtnetlink_rcv_msg+0x2fd/0x8b0
[   86.051955]  netlink_rcv_skb+0x11c/0x340
[   86.051955]  netlink_unicast+0x439/0x630
[   86.051955]  netlink_sendmsg+0x752/0xc00
[   86.051955]  sock_sendmsg+0xdd/0x110
[   86.051955]  __sys_sendto+0x1cc/0x2a0
[   86.051955]  __x64_sys_sendto+0xd8/0x1b0
[   86.051955]  do_syscall_64+0x3a/0x80
[   86.051955]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   86.051955]
[   86.051955] Freed by task 301:
[   86.051955]  kasan_save_stack+0x1c/0x40
[   86.051955]  kasan_set_track+0x21/0x30
[   86.051955]  kasan_set_free_info+0x20/0x30
[   86.051955]  __kasan_slab_free+0x104/0x170
[   86.051955]  kfree+0x8c/0x290
[   86.051955]  mctp_dev_notify+0x161/0x2c0
[   86.051955]  raw_notifier_call_chain+0x8b/0xc0
[   86.051955]  unregister_netdevice_many+0x299/0x1180
[   86.051955]  unregister_netdevice_queue+0x210/0x2f0
[   86.051955]  unregister_netdev+0x13/0x20
[   86.051955]  mctp_serial_close+0x6d/0xa0
[   86.051955]  tty_ldisc_kill+0x31/0xa0
[   86.051955]  tty_ldisc_hangup+0x24f/0x560
[   86.051955]  __tty_hangup.part.28+0x2ce/0x6b0
[   86.051955]  tty_release+0x327/0xc70
[   86.051955]  __fput+0x1df/0x8b0
[   86.051955]  task_work_run+0xca/0x150
[   86.051955]  exit_to_user_mode_prepare+0x114/0x120
[   86.051955]  syscall_exit_to_user_mode+0x12/0x20
[   86.051955]  do_syscall_64+0x46/0x80
[   86.051955]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   86.051955]
[   86.051955] The buggy address belongs to the object at ffff888005f298c0
[   86.051955]  which belongs to the cache kmalloc-8 of size 8
[   86.051955] The buggy address is located 0 bytes inside of
[   86.051955]  8-byte region [ffff888005f298c0, ffff888005f298c8)
[   86.051955]
[   86.051955] The buggy address belongs to the physical page:
[   86.051955] flags: 0x100000000000200(slab|node=0|zone=1)
[   86.051955] raw: 0100000000000200 dead000000000100 dead000000000122 ffff888005c42280
[   86.051955] raw: 0000000000000000 0000000080660066 00000001ffffffff 0000000000000000
[   86.051955] page dumped because: kasan: bad access detected
[   86.051955]
[   86.051955] Memory state around the buggy address:
[   86.051955]  ffff888005f29780: 00 fc fc fc fc 00 fc fc fc fc 00 fc fc fc fc 00
[   86.051955]  ffff888005f29800: fc fc fc fc 00 fc fc fc fc 00 fc fc fc fc 00 fc
[   86.051955] >ffff888005f29880: fc fc fc fb fc fc fc fc fa fc fc fc fc fa fc fc
[   86.051955]                                            ^
[   86.051955]  ffff888005f29900: fc fc 00 fc fc fc fc 00 fc fc fc fc 00 fc fc fc
[   86.051955]  ffff888005f29980: fc 00 fc fc fc fc 00 fc fc fc fc 00 fc fc fc fc
[   86.051955] ==================================================================

To this end, just like the commit e0448092 ("Bluetooth: defer
cleanup of resources in hci_unregister_dev()")  this patch defers the
destructive kfree(mdev->addrs) in mctp_unregister to the mctp_dev_put,
where the refcount of mdev is zero and the entire device is reclaimed.
This prevents the use-after-free because the sendmsg thread holds the
reference of mdev in the mctp_route object.

Fixes: 583be982 (mctp: Add device handling and netlink interface)
Signed-off-by: Lin Ma <linma@zju.edu.cn>
Acked-by: Jeremy Kerr <jk@codeconstruct.com.au>
Link: https://lore.kernel.org/r/20220422114340.32346-1-linma@zju.edu.cnSigned-off-by: Paolo Abeni <pabeni@redhat.com>

Wen Gu says:

====================
net/smc: Two fixes for smc fallback

This patch set includes two fixes for smc fallback:

Patch 1/2 introduces some simple helpers to wrap the replacement
and restore of clcsock's callback functions. Make sure that only
the original callbacks will be saved and not overwritten.

Patch 2/2 fixes a syzbot reporting slab-out-of-bound issue where
smc_fback_error_report() accesses the already freed smc sock (see
https://lore.kernel.org/r/00000000000013ca8105d7ae3ada@google.com/).
The patch fixes it by resetting sk_user_data and restoring clcsock
callback functions timely in fallback situation.

But it should be noted that although patch 2/2 can fix the issue
of 'slab-out-of-bounds/use-after-free in smc_fback_error_report',
it can't pass the syzbot reproducer test. Because after applying
these two patches in upstream, syzbot reproducer triggered another
known issue like this:

==================================================================
BUG: KASAN: use-after-free in tcp_retransmit_timer+0x2ef3/0x3360 net/ipv4/tcp_timer.c:511
Read of size 8 at addr ffff888020328380 by task udevd/4158

CPU: 1 PID: 4158 Comm: udevd Not tainted 5.18.0-rc3-syzkaller-00074-gb05a5683-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
  __dump_stack lib/dump_stack.c:88 [inline]
  dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
  print_address_description.constprop.0.cold+0xeb/0x467 mm/kasan/report.c:313
  print_report mm/kasan/report.c:429 [inline]
  kasan_report.cold+0xf4/0x1c6 mm/kasan/report.c:491
  tcp_retransmit_timer+0x2ef3/0x3360 net/ipv4/tcp_timer.c:511
  tcp_write_timer_handler+0x5e6/0xbc0 net/ipv4/tcp_timer.c:622
  tcp_write_timer+0xa2/0x2b0 net/ipv4/tcp_timer.c:642
  call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421
  expire_timers kernel/time/timer.c:1466 [inline]
  __run_timers.part.0+0x679/0xa80 kernel/time/timer.c:1737
  __run_timers kernel/time/timer.c:1715 [inline]
  run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1750
  __do_softirq+0x29b/0x9c2 kernel/softirq.c:558
  invoke_softirq kernel/softirq.c:432 [inline]
  __irq_exit_rcu+0x123/0x180 kernel/softirq.c:637
  irq_exit_rcu+0x5/0x20 kernel/softirq.c:649
  sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097
 </IRQ>
 ...
(detail report can be found in https://syzkaller.appspot.com/text?tag=CrashReport&x=15406b44f00000)

IMHO, the above issue is the same as this known one: https://syzkaller.appspot.com/bug?extid=694120e1002c117747ed,
and it doesn't seem to be related with SMC. The discussion about this known issue is ongoing and can be found in
https://lore.kernel.org/bpf/000000000000f75af905d3ba0716@google.com/T/.

And I added the temporary solution mentioned in the above discussion on
top of my two patches, the syzbot reproducer of 'slab-out-of-bounds/
use-after-free in smc_fback_error_report' no longer triggers any issue.
====================

Link: https://lore.kernel.org/r/1650614179-11529-1-git-send-email-guwen@linux.alibaba.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

syzbot reported a slab-out-of-bounds/use-after-free issue,
which was caused by accessing an already freed smc sock in
fallback-specific callback functions of clcsock.

This patch fixes the issue by restoring fallback-specific
callback functions to original ones and resetting clcsock
sk_user_data to NULL before freeing smc sock.

Meanwhile, this patch introduces sk_callback_lock to make
the access and assignment to sk_user_data mutually exclusive.

Reported-by: syzbot+b425899ed22c6943e00b@syzkaller.appspotmail.com
Fixes: 341adeec ("net/smc: Forward wakeup to smc socket waitqueue after fallback")
Link: https://lore.kernel.org/r/00000000000013ca8105d7ae3ada@google.com/Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
Acked-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Both listen and fallback process will save the current clcsock
callback functions and establish new ones. But if both of them
happen, the saved callback functions will be overwritten.

So this patch introduces some helpers to ensure that only save
the original callback functions of clcsock.

Fixes: 341adeec ("net/smc: Forward wakeup to smc socket waitqueue after fallback")
Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
Acked-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

syzbot complained about a recent change in TCP stack,
hitting a NULL pointer [1]

tcp request sockets have an af_specific pointer, which
was used before the blamed change only for SYNACK generation
in non SYNCOOKIE mode.

tcp requests sockets momentarily created when third packet
coming from client in SYNCOOKIE mode were not using
treq->af_specific.

Make sure this field is populated, in the same way normal
TCP requests sockets do in tcp_conn_request().

[1]
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
CPU: 1 PID: 3695 Comm: syz-executor864 Not tainted 5.18.0-rc3-syzkaller-00224-g5fd1fe48 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:tcp_create_openreq_child+0xe16/0x16b0 net/ipv4/tcp_minisocks.c:534
Code: 48 c1 ea 03 80 3c 02 00 0f 85 e5 07 00 00 4c 8b b3 28 01 00 00 48 b8 00 00 00 00 00 fc ff df 49 8d 7e 08 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 c9 07 00 00 48 8b 3c 24 48 89 de 41 ff 56 08 48
RSP: 0018:ffffc90000de0588 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff888076490330 RCX: 0000000000000100
RDX: 0000000000000001 RSI: ffffffff87d67ff0 RDI: 0000000000000008
RBP: ffff88806ee1c7f8 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff87d67f00 R11: 0000000000000000 R12: ffff88806ee1bfc0
R13: ffff88801b0e0368 R14: 0000000000000000 R15: 0000000000000000
FS:  00007f517fe58700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffcead76960 CR3: 000000006f97b000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 tcp_v6_syn_recv_sock+0x199/0x23b0 net/ipv6/tcp_ipv6.c:1267
 tcp_get_cookie_sock+0xc9/0x850 net/ipv4/syncookies.c:207
 cookie_v6_check+0x15c3/0x2340 net/ipv6/syncookies.c:258
 tcp_v6_cookie_check net/ipv6/tcp_ipv6.c:1131 [inline]
 tcp_v6_do_rcv+0x1148/0x13b0 net/ipv6/tcp_ipv6.c:1486
 tcp_v6_rcv+0x3305/0x3840 net/ipv6/tcp_ipv6.c:1725
 ip6_protocol_deliver_rcu+0x2e9/0x1900 net/ipv6/ip6_input.c:422
 ip6_input_finish+0x14c/0x2c0 net/ipv6/ip6_input.c:464
 NF_HOOK include/linux/netfilter.h:307 [inline]
 NF_HOOK include/linux/netfilter.h:301 [inline]
 ip6_input+0x9c/0xd0 net/ipv6/ip6_input.c:473
 dst_input include/net/dst.h:461 [inline]
 ip6_rcv_finish net/ipv6/ip6_input.c:76 [inline]
 NF_HOOK include/linux/netfilter.h:307 [inline]
 NF_HOOK include/linux/netfilter.h:301 [inline]
 ipv6_rcv+0x27f/0x3b0 net/ipv6/ip6_input.c:297
 __netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5405
 __netif_receive_skb+0x24/0x1b0 net/core/dev.c:5519
 process_backlog+0x3a0/0x7c0 net/core/dev.c:5847
 __napi_poll+0xb3/0x6e0 net/core/dev.c:6413
 napi_poll net/core/dev.c:6480 [inline]
 net_rx_action+0x8ec/0xc60 net/core/dev.c:6567
 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558
 invoke_softirq kernel/softirq.c:432 [inline]
 __irq_exit_rcu+0x123/0x180 kernel/softirq.c:637
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:649
 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097

Fixes: 5b0b9e4c ("tcp: md5: incorrect tcp_header_len for incoming connections")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Francesco Ruggeri <fruggeri@arista.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

I had this bug sitting for too long in my pile, it is time to fix it.

Thanks to Doug Porter for reminding me of it!

We had various attempts in the past, including commit
0cbe6a8f ("tcp: remove SOCK_QUEUE_SHRUNK"),
but the issue is that TCP stack currently only generates
EPOLLOUT from input path, when tp->snd_una has advanced
and skb(s) cleaned from rtx queue.

If a flow has a big RTT, and/or receives SACKs, it is possible
that the notsent part (tp->write_seq - tp->snd_nxt) reaches 0
and no more data can be sent until tp->snd_una finally advances.

What is needed is to also check if POLLOUT needs to be generated
whenever tp->snd_nxt is advanced, from output path.

This bug triggers more often after an idle period, as
we do not receive ACK for at least one RTT. tcp_notsent_lowat
could be a fraction of what CWND and pacing rate would allow to
send during this RTT.

In a followup patch, I will remove the bogus call
to tcp_chrono_stop(sk, TCP_CHRONO_SNDBUF_LIMITED)
from tcp_check_space(). Fact that we have decided to generate
an EPOLLOUT does not mean the application has immediately
refilled the transmit queue. This optimistic call
might have been the reason the bug seemed not too serious.

Tested:

200 ms rtt, 1% packet loss, 32 MB tcp_rmem[2] and tcp_wmem[2]

$ echo 500000 >/proc/sys/net/ipv4/tcp_notsent_lowat
$ cat bench_rr.sh
SUM=0
for i in {1..10}
do
 V=`netperf -H remote_host -l30 -t TCP_RR -- -r 10000000,10000 -o LOCAL_BYTES_SENT | egrep -v "MIGRATED|Bytes"`
 echo $V
 SUM=$(($SUM + $V))
done
echo SUM=$SUM

Before patch:
$ bench_rr.sh
130000000
80000000
140000000
140000000
140000000
140000000
130000000
40000000
90000000
110000000
SUM=1140000000

After patch:
$ bench_rr.sh
430000000
590000000
530000000
450000000
450000000
350000000
450000000
490000000
480000000
460000000
SUM=4680000000  # This is 410 % of the value before patch.

Fixes: c9bee3b7 ("tcp: TCP_NOTSENT_LOWAT socket option")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Doug Porter <dsp@fb.com>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

DSA, through dsa_port_bridge_leave(), first notifies the port of the
fact that it left a bridge, then, if that bridge was VLAN-aware, it
notifies the port of the change in VLAN awareness state, towards
VLAN-unaware mode.

So ocelot_port_vlan_filtering() can be called when ocelot_port->bridge
is NULL, and this makes ocelot_add_vlan_unaware_pvid() create a struct
ocelot_bridge_vlan with a vid of 0 and an "untagged" setting of true on
that port.

In a way this structure correctly reflects the reality, but by design,
VID 0 (OCELOT_STANDALONE_PVID) was not meant to be kept in the bridge
VLAN list of the driver, but managed separately.

Having OCELOT_STANDALONE_PVID in ocelot->vlans makes us trip up on
several sanity checks that did not expect to have this VID there.
For example, after we leave a VLAN-aware bridge and we re-join it, we
can no longer program egress-tagged VLANs to hardware:

 # ip link add br0 type bridge vlan_filtering 1 && ip link set br0 up
 # ip link set swp0 master br0
 # ip link set swp0 nomaster
 # ip link set swp0 master br0
 # bridge vlan add dev swp0 vid 100
Error: mscc_ocelot_switch_lib: Port with more than one egress-untagged VLAN cannot have egress-tagged VLANs.

But this configuration is in fact supported by the hardware, since we
could use OCELOT_PORT_TAG_NATIVE. According to its comment:

/* all VLANs except the native VLAN and VID 0 are egress-tagged */

yet when assessing the eligibility for this mode, we do not check for
VID 0 in ocelot_port_uses_native_vlan(), instead we just ensure that
ocelot_port_num_untagged_vlans() == 1. This is simply because VID 0
doesn't have a bridge VLAN structure.

The way I identify the problem is that ocelot_port_vlan_filtering(false)
only means to call ocelot_add_vlan_unaware_pvid() when we dynamically
turn off VLAN awareness for a bridge we are under, and the PVID changes
from the bridge PVID to a reserved PVID based on the bridge number.

Since OCELOT_STANDALONE_PVID is statically added to the VLAN table
during ocelot_vlan_init() and never removed afterwards, calling
ocelot_add_vlan_unaware_pvid() for it is not intended and does not serve
any purpose.

Fix the issue by avoiding the call to ocelot_add_vlan_unaware_pvid(vid=0)
when we're resetting VLAN awareness after leaving the bridge, to become
a standalone port.

Fixes: 54c31984 ("net: mscc: ocelot: enforce FDB isolation when VLAN-unaware")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Both the felix DSA driver and ocelot switchdev driver declare
dev->features & NETIF_F_HW_VLAN_CTAG_FILTER under certain circumstances*,
so the 8021q module will add VID 0 to our RX filter when the port goes
up, to ensure 802.1p traffic is not dropped.

We treat VID 0 as a special value (OCELOT_STANDALONE_PVID) which
deliberately does not have a struct ocelot_bridge_vlan associated with
it. Instead, this gets programmed to the VLAN table in ocelot_vlan_init().

If we allow external calls to modify VID 0, we reach the following
situation:

 # ip link add br0 type bridge vlan_filtering 1 && ip link set br0 up
 # ip link set swp0 master br0
 # ip link set swp0 up # this adds VID 0 to ocelot->vlans with untagged=false
bridge vlan
port              vlan-id
swp0              1 PVID Egress Untagged # the bridge also adds VID 1
br0               1 PVID Egress Untagged
 # bridge vlan add dev swp0 vid 100 untagged
Error: mscc_ocelot_switch_lib: Port with egress-tagged VLANs cannot have more than one egress-untagged (native) VLAN.

This configuration should have been accepted, because
ocelot_port_manage_port_tag() should select OCELOT_PORT_TAG_NATIVE.
Yet it isn't, because we have an entry in ocelot->vlans which says
VID 0 should be egress-tagged, something the hardware can't do.

Fix this by suppressing additions/deletions on VID 0 and managing this
VLAN exclusively using OCELOT_STANDALONE_PVID.

*DSA toggles it when the port becomes VLAN-aware by joining a VLAN-aware
bridge. Ocelot declares it unconditionally for some reason.

Fixes: 54c31984 ("net: mscc: ocelot: enforce FDB isolation when VLAN-unaware")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Certain DSA switches can eliminate flooding to the CPU when none of the
ports have the IFF_ALLMULTI or IFF_PROMISC flags set. This is done by
synthesizing a call to dsa_port_bridge_flags() for the CPU port, a call
which normally comes from the bridge driver via switchdev.

The bridge port flags and IFF_PROMISC|IFF_ALLMULTI have slightly
different semantics, and due to inattention/lack of proper testing, the
IFF_PROMISC flag allows unknown unicast to be flooded to the CPU, but
not unknown multicast.

This must be fixed by setting both BR_FLOOD (unicast) and BR_MCAST_FLOOD
in the synthesized dsa_port_bridge_flags() call, since IFF_PROMISC means
that packets should not be filtered regardless of their MAC DA.

Fixes: 7569459a ("net: dsa: manage flooding on the CPU ports")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

As pointed out by Jakub Kicinski, currently using TUNNEL_SEQ in
collect_md mode is racy for [IP6]GRE[TAP] devices.  Consider the
following sequence of events:

1. An [IP6]GRE[TAP] device is created in collect_md mode using "ip link
   add ... external".  "ip" ignores "[o]seq" if "external" is specified,
   so TUNNEL_SEQ is off, and the device is marked as NETIF_F_LLTX (i.e.
   it uses lockless TX);
2. Someone sets TUNNEL_SEQ on outgoing skb's, using e.g.
   bpf_skb_set_tunnel_key() in an eBPF program attached to this device;
3. gre_fb_xmit() or __gre6_xmit() processes these skb's:

	gre_build_header(skb, tun_hlen,
			 flags, protocol,
			 tunnel_id_to_key32(tun_info->key.tun_id),
			 (flags & TUNNEL_SEQ) ? htonl(tunnel->o_seqno++)
					      : 0);   ^^^^^^^^^^^^^^^^^

Since we are not using the TX lock (&txq->_xmit_lock), multiple CPUs may
try to do this tunnel->o_seqno++ in parallel, which is racy.  Fix it by
making o_seqno atomic_t.

As mentioned by Eric Dumazet in commit b790e01a ("ip_gre: lockless
xmit"), making o_seqno atomic_t increases "chance for packets being out
of order at receiver" when NETIF_F_LLTX is on.

Maybe a better fix would be:

1. Do not ignore "oseq" in external mode.  Users MUST specify "oseq" if
   they want the kernel to allow sequencing of outgoing packets;
2. Reject all outgoing TUNNEL_SEQ packets if the device was not created
   with "oseq".

Unfortunately, that would break userspace.

We could now make [IP6]GRE[TAP] devices always NETIF_F_LLTX, but let us
do it in separate patches to keep this fix minimal.
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Fixes: 77a5196a ("gre: add sequence number for collect md mode.")
Signed-off-by: Peilin Ye <peilin.ye@bytedance.com>
Acked-by: William Tu <u9012063@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

For IP6GRE and IP6GRETAP devices, currently o_seqno starts from 1 in
native mode.  According to RFC 2890 2.2., "The first datagram is sent
with a sequence number of 0."  Fix it.

It is worth mentioning that o_seqno already starts from 0 in collect_md
mode, see the "if (tunnel->parms.collect_md)" clause in __gre6_xmit(),
where tunnel->o_seqno is passed to gre_build_header() before getting
incremented.

Fixes: c12b395a ("gre: Support GRE over IPv6")
Signed-off-by: Peilin Ye <peilin.ye@bytedance.com>
Acked-by: William Tu <u9012063@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

For GRE and GRETAP devices, currently o_seqno starts from 1 in native
mode.  According to RFC 2890 2.2., "The first datagram is sent with a
sequence number of 0."  Fix it.

It is worth mentioning that o_seqno already starts from 0 in collect_md
mode, see gre_fb_xmit(), where tunnel->o_seqno is passed to
gre_build_header() before getting incremented.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: Peilin Ye <peilin.ye@bytedance.com>
Acked-by: William Tu <u9012063@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The lan966x->ports[] array has lan966x->num_phys_ports elements.  These
are assigned in lan966x_probe().  That means the > comparison should be
changed to >=.

The first off by one check is harmless but the second one could lead to
an out of bounds access and a crash.

Fixes: 5ccd66e0 ("net: lan966x: add support for interrupts from analyzer")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

In the current implementation, when TCP initiates a connection
to an unavailable [ip,port], ECONNREFUSED will be stored in the
TCP socket, but SMC will not. However, some apps (like curl) use
getsockopt(,,SO_ERROR,,) to get the error information, which makes
them miss the error message and behave strangely.

Fixes: 50717a37 ("net/smc: nonblocking connect rework")
Signed-off-by: liuyacan <liuyacan@corp.netease.com>
Reviewed-by: Tony Lu <tonylu@linux.alibaba.com>
Acked-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

In one of the error paths of the device_for_each_child_node() loop
in hns_mac_init, add missing call to fwnode_handle_put.
Signed-off-by: Peng Wu <wupeng58@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Guangbin Huang says:

====================
net: hns3: add some fixes for -net

This series adds some fixes for the HNS3 ethernet driver.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Currently, there are some querying mailboxes sent from VF to PF,
and VF will wait the PF's handling result. For mailbox
HCLGE_MBX_GET_QID_IN_PF and HCLGE_MBX_GET_RSS_KEY, it may fail
when the input parameter is invalid, but the prototype of their
handler function is void. In this case, PF always return success
to VF, which may cause the VF get incorrect result.

Fixes it by adding return value for these function.

Fixes: 63b1279d ("net: hns3: check queue id range before using")
Fixes: 532cfc0d ("net: hns3: add a check for index in hclge_get_rss_key()")
Signed-off-by: Jian Shen <shenjian15@huawei.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Add validity check for message data length in function
hclge_send_mbx_msg(), avoid unexpected overflow.

Fixes: dde1a86e ("net: hns3: Add mailbox support to PF driver")
Signed-off-by: Jian Shen <shenjian15@huawei.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Currently, function hclge_get_ring_chain_from_mbx will return -ENOMEM if
ring_num is bigger than HCLGE_MBX_MAX_RING_CHAIN_PARAM_NUM. It is better to
return -EINVAL for the invalid parameter case.

So this patch fixes it by return -EINVAL in this abnormal branch.

Fixes: 5d02a58d ("net: hns3: fix for buffer overflow smatch warning")
Signed-off-by: Jie Wang <wangjie125@huawei.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The comments in function hclge_comm_tqps_update_stats is not right,
so fix it.

Fixes: 287db5c4 ("net: hns3: create new set of common tqp stats APIs for PF and VF reuse")
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

For debugfs node rx/tx_queue_info and rx/tx_bd_info, their output info is
aligned to the right, it's not aligned with output of other debugfs node,
so uniform their output info.

Fixes: 907676b1 ("net: hns3: use tx bounce buffer for small packets")
Fixes: e44c495d ("net: hns3: refactor queue info of debugfs")
Fixes: 77e91848 ("net: hns3: refactor dump bd info of debugfs")
Signed-off-by: Hao Chen <chenhao288@hisilicon.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

If failed to register netdev, it needs to clear INITED state and stop
client in case of cause problem when concurrency with uninitialized
process of driver.

Fixes: a289a7e5 ("net: hns3: put off calling register_netdev() until client initialize complete")
Signed-off-by: Jian Shen <shenjian15@huawei.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Pablo Neira Ayuso says:

====================
Netfilter fixes for net

The following patchset contains Netfilter fixes for net:

1) Fix incorrect printing of memory size of IPVS connection hash table,
   from Pengcheng Yang.

2) Fix spurious EEXIST errors in nft_set_rbtree.

3) Remove leftover empty flowtable file, from  Rongguang Wei.

4) Fix ip6_route_me_harder() with vrf driver, from Martin Willi.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

The commit referenced below fixed packet re-routing if Netfilter mangles
a routing key property of a packet and the packet is routed in a VRF L3
domain. The fix, however, addressed IPv4 re-routing, only.

This commit applies the same behavior for IPv6. While at it, untangle
the nested ternary operator to make the code more readable.

Fixes: 6d8b49c3 ("netfilter: Update ip_route_me_harder to consider L3 domain")
Cc: stable@vger.kernel.org
Signed-off-by: Martin Willi <martin@strongswan.org>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

CONFIG_NF_FLOW_TABLE_IPV4 is already removed and the real user is also
removed(nf_flow_table_ipv4.c is empty).

Fixes: c42ba429 ("netfilter: flowtable: remove ipv4/ipv6 modules")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

A null pointer reference issue can be triggered when the response of a
stream reconf request arrives after the timer is triggered, such as:

  send Incoming SSN Reset Request --->
  CPU0:
   reconf timer is triggered,
   go to the handler code before hold sk lock
                            <--- reply with Outgoing SSN Reset Request
  CPU1:
   process Outgoing SSN Reset Request,
   and set asoc->strreset_chunk to NULL
  CPU0:
   continue the handler code, hold sk lock,
   and try to hold asoc->strreset_chunk, crash!

In Ying Xu's testing, the call trace is:

  [ ] BUG: kernel NULL pointer dereference, address: 0000000000000010
  [ ] RIP: 0010:sctp_chunk_hold+0xe/0x40 [sctp]
  [ ] Call Trace:
  [ ]  <IRQ>
  [ ]  sctp_sf_send_reconf+0x2c/0x100 [sctp]
  [ ]  sctp_do_sm+0xa4/0x220 [sctp]
  [ ]  sctp_generate_reconf_event+0xbd/0xe0 [sctp]
  [ ]  call_timer_fn+0x26/0x130

This patch is to fix it by returning from the timer handler if asoc
strreset_chunk is already set to NULL.

Fixes: 7b9438de ("sctp: add stream reconf timer")
Reported-by: Ying Xu <yinxu@redhat.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>