A card's close_dev work is scheduled on a driver-wide workqueue. If the
card is removed and freed while the work is still active, this causes a
use-after-free.
So make sure that the work is completed before freeing the card.

Fixes: 0f54761d ("qeth: Support VEPA mode")
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The error path in qeth_alloc_qdio_buffers() that takes care of
cleaning up the Output Queues is buggy. It first frees the queue, but
then calls qeth_clear_outq_buffers() with that very queue struct.

Make the call to qeth_clear_outq_buffers() part of the free action
(in the correct order), and while at it fix the naming of the helper.

Fixes: 0da9581d ("qeth: exploit asynchronous delivery of storage blocks")
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Alexandra Winter <wintera@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Whenever we fail before/while starting an IO, make sure to release the
IO buffer. Usually qeth_irq() would do this for us, but if the IO
doesn't even start we obviously won't get an interrupt for it either.
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

In fl_change(), when adding a new rule (i.e. fold == NULL), a driver may
reject the new rule, for example due to resource exhaustion. By that
point, the new rule was already assigned a mask, and it was added to
that mask's hash table. The clean-up path that's invoked as a result of
the rejection however neglects to undo the hash table addition, and
proceeds to free the new rule, thus leaving a dangling pointer in the
hash table.

Fix by removing fnew from the mask's hash table before it is freed.

Fixes: 35cc3cef ("net/sched: cls_flower: Reject duplicated rules also under skip_sw")
Signed-off-by: Petr Machata <petrm@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Merge tag 'wireless-drivers-for-davem-2019-02-04' of git://git.kernel.org/pub/scm/linux/kernel/git/kvalo/wireless-drivers

Kalle Valo says:

====================
wireless-drivers fixes for 5.0

First set of small, but importnat, fixes for 5.0.

iwlwifi

* fix a build regression introduced in 5.0-rc1

wlcore

* fix a firmware regression from v4.18-rc1

mt76x0

* fix for configuring tx power from user space

ath10k

* fix wcn3990 regression from v4.20-rc1
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Ursula Braun says:

====================
net/smc: fixes 2019-02-04

here are more fixes in the smc code for the net tree:
Patch 1 fixes an IB-related problem with SMCR.
Patch 2 fixes a cursor problem for one-way traffic.
Patch 3 fixes a problem with RMB-reusage.
Patch 4 fixes a closing issue.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

If some kind of closing is received from the peer while still in
state SMC_INIT, it means the peer has had an active connection and
closed the socket quickly before listen_work finished. This should
not result in a shortcut from state SMC_INIT to state SMC_CLOSED.
This patch adds the socket to the accept queue in state
SMC_APPCLOSEWAIT1. The socket reaches state SMC_CLOSED once being
accepted and closed with smc_release().
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Once RMBs are flagged as unused they are candidates for reuse.
Thus the LLC DELETE RKEY operaton should be made before flagging
the RMB as unused.

Fixes: c7674c00 ("net/smc: unregister rkeys of unused buffer")
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

In some scenarios a separate consumer cursor update is necessary.
The decision is made in smc_tx_consumer_cursor_update(). The
sender_free computation could be wrong:

The rx confirmed cursor is always smaller than or equal to the
rx producer cursor. The parameters in the smc_curs_diff() call
have to be exchanged, otherwise sender_free might even be negative.

And if more data arrives local_rx_ctrl.prod might be updated, enabling
a cursor difference between local_rx_ctrl.prod and rx confirmed cursor
larger than the RMB size. This case is not covered by smc_curs_diff().
Thus function smc_curs_diff_large() is introduced here.

If a recvmsg() is processed in parallel, local_tx_ctrl.cons might
change during smc_cdc_msg_send. Make sure rx_curs_confirmed is updated
with the actually sent local_tx_ctrl.cons value.

Fixes: e82f2e31 ("net/smc: optimize consumer cursor updates")
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The work requests for rdma writes are built in local variables within
function smc_tx_rdma_write(). This violates the rule that the work
request storage has to stay till the work request is confirmed by
a completion queue response.
This patch introduces preallocated memory for these work requests.
The storage is allocated, once a link (and thus a queue pair) is
established.
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

During sendmsg() a cloned skb is saved via dp83640_txtstamp() in
->tx_queue. After the NIC sends this packet, the PHY will reply with a
timestamp for that TX packet. If the cable is pulled at the right time I
don't see that packet. It might gets flushed as part of queue shutdown
on NIC's side.
Once the link is up again then after the next sendmsg() we enqueue
another skb in dp83640_txtstamp() and have two on the list. Then the PHY
will send a reply and decode_txts() attaches it to the first skb on the
list.
No crash occurs since refcounting works but we are one packet behind.
linuxptp/ptp4l usually closes the socket and opens a new one (in such a
timeout case) so those "stale" replies never get there. However it does
not resume normal operation anymore.

Purge old skbs in decode_txts().

Fixes: cb646e2b ("ptp: Added a clock driver for the National Semiconductor PHYTER.")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Kurt Kanzenbach <kurt@linutronix.de>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Previously virtnet_xdp_xmit() did not account for device tx counters,
which caused confusions.
To be consistent with SKBs, account them on freeing xdp_frames.
Reported-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Now when using stream reconfig to add out streams, stream->out
will get re-allocated, and all old streams' information will
be copied to the new ones and the old ones will be freed.

So without stream->out_curr updated, next time when trying to
send from stream->out_curr stream, a panic would be caused.

This patch is to check and update stream->out_curr when
allocating stream_out.

v1->v2:
  - define fa_index() to get elem index from stream->out_curr.
v2->v3:
  - repost with no change.

Fixes: 5bbbbe32 ("sctp: introduce stream scheduler foundations")
Reported-by: Ying Xu <yinxu@redhat.com>
Reported-by: syzbot+e33a3a138267ca119c7d@syzkaller.appspotmail.com
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Create an entry for Redpine wireless driver and add Amit and myself as
maintainers.
Signed-off-by: Siva Rebbagondla <siva.rebbagondla@redpinesignals.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

Broadcom STB chips support a deep sleep mode where all register
contents are lost. Because we were stashing the MagicPacket password
into some of these registers a suspend into that deep sleep then a
resumption would not lead to being able to wake-up from MagicPacket with
password again.

Fix this by keeping a software copy of the password and program it
during suspend.

Fixes: 83e82f4c ("net: systemport: add Wake-on-LAN support")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Stefano Garzarella says:

====================
vsock/virtio: fix issues on device hot-unplug

These patches try to handle the hot-unplug of vsock virtio transport device in
a proper way.

Maybe move the vsock_core_init()/vsock_core_exit() functions in the module_init
and module_exit of vsock_virtio_transport module can't be the best way, but the
architecture of vsock_core forces us to this approach for now.

The vsock_core proto_ops expect a valid pointer to the transport device, so we
can't call vsock_core_exit() until there are open sockets.

v2 -> v3:
 - Rebased on master

v1 -> v2:
 - Fixed commit message of patch 1.
 - Added Reviewed-by, Acked-by tags by Stefan
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

When the virtio transport device disappear, we should reset all
connected sockets in order to inform the users.
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

virtio_vsock_remove() invokes the vsock_core_exit() also if there
are opened sockets for the AF_VSOCK protocol family. In this way
the vsock "transport" pointer is set to NULL, triggering the
kernel panic at the first socket activity.

This patch move the vsock_core_init()/vsock_core_exit() in the
virtio_vsock respectively in module_init and module_exit functions,
that cannot be invoked until there are open sockets.

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1609699Reported-by: Yan Fu <yafu@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

This reverts commit 6623c0fb.

The original diagnosis was incorrect: it appears that the NIC had
PHY polling mode enabled, which meant that it overwrote the PHYs
advertisement register during negotiation.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Tested-by: Yonglong Liu <liuyonglong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Alexei Starovoitov says:

====================
pull-request: bpf 2019-01-31

The following pull-request contains BPF updates for your *net* tree.

The main changes are:

1) disable preemption in sender side of socket filters, from Alexei.

2) fix two potential deadlocks in syscall bpf lookup and prog_register,
   from Martin and Alexei.

3) fix BTF to allow typedef on func_proto, from Yonghong.

4) two bpftool fixes, from Jiri and Paolo.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Similarly to commit 276bdb82 ("dccp: check ccid before dereferencing")
it is wise to test for a NULL ccid.

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 16 Comm: ksoftirqd/1 Not tainted 5.0.0-rc3+ #37
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:ccid_hc_tx_parse_options net/dccp/ccid.h:205 [inline]
RIP: 0010:dccp_parse_options+0x8d9/0x12b0 net/dccp/options.c:233
Code: c5 0f b6 75 b3 80 38 00 0f 85 d6 08 00 00 48 b9 00 00 00 00 00 fc ff df 48 8b 45 b8 4c 8b b8 f8 07 00 00 4c 89 f8 48 c1 e8 03 <80> 3c 08 00 0f 85 95 08 00 00 48 b8 00 00 00 00 00 fc ff df 4d 8b
kobject: 'loop5' (0000000080f78fc1): kobject_uevent_env
RSP: 0018:ffff8880a94df0b8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8880858ac723 RCX: dffffc0000000000
RDX: 0000000000000100 RSI: 0000000000000007 RDI: 0000000000000001
RBP: ffff8880a94df140 R08: 0000000000000001 R09: ffff888061b83a80
R10: ffffed100c370752 R11: ffff888061b83a97 R12: 0000000000000026
R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0defa33518 CR3: 000000008db5e000 CR4: 00000000001406e0
kobject: 'loop5' (0000000080f78fc1): fill_kobj_path: path = '/devices/virtual/block/loop5'
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 dccp_rcv_state_process+0x2b6/0x1af6 net/dccp/input.c:654
 dccp_v4_do_rcv+0x100/0x190 net/dccp/ipv4.c:688
 sk_backlog_rcv include/net/sock.h:936 [inline]
 __sk_receive_skb+0x3a9/0xea0 net/core/sock.c:473
 dccp_v4_rcv+0x10cb/0x1f80 net/dccp/ipv4.c:880
 ip_protocol_deliver_rcu+0xb6/0xa20 net/ipv4/ip_input.c:208
 ip_local_deliver_finish+0x23b/0x390 net/ipv4/ip_input.c:234
 NF_HOOK include/linux/netfilter.h:289 [inline]
 NF_HOOK include/linux/netfilter.h:283 [inline]
 ip_local_deliver+0x1f0/0x740 net/ipv4/ip_input.c:255
 dst_input include/net/dst.h:450 [inline]
 ip_rcv_finish+0x1f4/0x2f0 net/ipv4/ip_input.c:414
 NF_HOOK include/linux/netfilter.h:289 [inline]
 NF_HOOK include/linux/netfilter.h:283 [inline]
 ip_rcv+0xed/0x620 net/ipv4/ip_input.c:524
 __netif_receive_skb_one_core+0x160/0x210 net/core/dev.c:4973
 __netif_receive_skb+0x2c/0x1c0 net/core/dev.c:5083
 process_backlog+0x206/0x750 net/core/dev.c:5923
 napi_poll net/core/dev.c:6346 [inline]
 net_rx_action+0x76d/0x1930 net/core/dev.c:6412
 __do_softirq+0x30b/0xb11 kernel/softirq.c:292
 run_ksoftirqd kernel/softirq.c:654 [inline]
 run_ksoftirqd+0x8e/0x110 kernel/softirq.c:646
 smpboot_thread_fn+0x6ab/0xa10 kernel/smpboot.c:164
 kthread+0x357/0x430 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
Modules linked in:
---[ end trace 58a0ba03bea2c376 ]---
RIP: 0010:ccid_hc_tx_parse_options net/dccp/ccid.h:205 [inline]
RIP: 0010:dccp_parse_options+0x8d9/0x12b0 net/dccp/options.c:233
Code: c5 0f b6 75 b3 80 38 00 0f 85 d6 08 00 00 48 b9 00 00 00 00 00 fc ff df 48 8b 45 b8 4c 8b b8 f8 07 00 00 4c 89 f8 48 c1 e8 03 <80> 3c 08 00 0f 85 95 08 00 00 48 b8 00 00 00 00 00 fc ff df 4d 8b
RSP: 0018:ffff8880a94df0b8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8880858ac723 RCX: dffffc0000000000
RDX: 0000000000000100 RSI: 0000000000000007 RDI: 0000000000000001
RBP: ffff8880a94df140 R08: 0000000000000001 R09: ffff888061b83a80
R10: ffffed100c370752 R11: ffff888061b83a97 R12: 0000000000000026
R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0defa33518 CR3: 0000000009871000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

Ursula Braun says:

====================
net/smc: fixes 2019-01-30

here are some fixes in different areas of the smc code for the net
tree.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Do not use pend->idx as index for the arrays because its value is
located in the cleared area. Use the existing local variable instead.
Without this fix the wrong area might be cleared.
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The device field of the IB event structure does not always point to the
SMC IB device. Load the pointer from the qp_context which is always
provided to smc_ib_qp_event_handler() in the priv field. And for qp
events the affected port is given in the qp structure of the ibevent,
derive it from there.
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Call smc_cdc_msg_send() under the connection send_lock to make sure all
send operations for one connection are serialized.
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

smc_cdc_get_free_slot() might wait for free transfer buffers when using
SMC-R. This wait should not be done under the send_lock, which is a
spin_lock. This fixes a cpu loop in parallel threads waiting for the
send_lock.
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

When a socket was connected and is now shut down for read, return 0 to
indicate end of data in recvmsg and splice_read (like TCP) and do not
return ENOTCONN. This behavior is required by the socket api.
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

When there is no more send buffer space and at least 1 byte was already
sent then return to user space. The wait is only done when no data was
sent by the sendmsg() call.
This fixes smc_tx_sendmsg() which tried to always send all user data and
started to wait for free send buffer space when needed. During this wait
the user space program was blocked in the sendmsg() call and hence not
able to receive incoming data. When both sides were in such a situation
then the connection stalled forever.
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

To prevent races between smc_lgr_terminate() and smc_conn_free() add an
extra check of the lgr field before accessing it, and cancel a delayed
free_work when a new smc connection is created.
This fixes the problem that free_work cleared the lgr variable but
smc_lgr_terminate() or smc_conn_free() still access it in parallel.
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Currently, users can only send pnetids with a maximum length of 15 bytes
over the SMC netlink interface although the maximum pnetid length is 16
bytes. This patch changes the SMC netlink policy to accept 16 byte
pnetids.
Signed-off-by: Hans Wippel <hwippel@linux.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Comparing an int to a size, which is unsigned, causes the int to become
unsigned, giving the wrong result. kernel_sendmsg can return a negative
error code.
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

In case of IPv6 pkts, ipv4_csum_ok is 0. Because of this, driver does
not set skb->ip_summed. So IPv6 rx checksum is not offloaded.
Signed-off-by: Govindarajulu Varadarajan <gvaradar@cisco.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

In sctp_sendmesg(), when walking the list of endpoint associations, the
association can be dropped from the list, making the list corrupt.
Properly handle this by using list_for_each_entry_safe()

Fixes: 49102805 ("sctp: add support for snd flag SCTP_SENDALL process in sendmsg")
Reported-by: Secunia Research <vuln@secunia.com>
Tested-by: Secunia Research <vuln@secunia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Simon Wunderlich says:

====================
Here are some batman-adv bugfixes:

 - Avoid WARN to report incorrect configuration, by Sven Eckelmann

 - Fix mac header position setting, by Sven Eckelmann

 - Fix releasing station statistics, by Felix Fietkau
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Merge tag 'mac80211-for-davem-2019-02-01' of git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211

Johannes Berg says:

====================
Two more fixes:
 * sometimes, not enough tailroom was allocated for
   software-encrypted management frames in mac80211
 * cfg80211 regulatory restore got an additional condition,
   needs to rerun the checks after that condition changes
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

The "p" buffer is 0x4000 bytes long.  B3_RI_WTO_R1 is 0x190.  The value
of "regs->len" is in the 1-0x4000 range.  The bug here is that
"regs->len - B3_RI_WTO_R1" can be a negative value which would lead to
memory corruption and an abrupt crash.

Fixes: c3f8be96 ("[PATCH] skge: expand ethtool debug register dump")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Since we now prevent regulatory restore during STA disconnect
if concurrent AP interfaces are active, we need to reschedule
this check when the AP state changes. This fixes never doing
a restore when an AP is the last interface to stop. Or to put
it another way: we need to re-check after anything we check
here changes.

Cc: stable@vger.kernel.org
Fixes: 113f3aaa ("cfg80211: Prevent regulatory restore during STA disconnect in concurrent interfaces")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Some drivers use IEEE80211_KEY_FLAG_SW_MGMT_TX to indicate that management
frames need to be software encrypted. Since normal data packets are still
encrypted by the hardware, crypto_tx_tailroom_needed_cnt gets decremented
after key upload to hw. This can lead to passing skbs to ccmp_encrypt_skb,
which don't have the necessary tailroom for software encryption.

Change the code to add tailroom for encrypted management packets, even if
crypto_tx_tailroom_needed_cnt is 0.

Cc: stable@vger.kernel.org
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Alexei Starovoitov says:

====================
v1->v2:
- reworded 2nd patch. It's a real dead lock. Not a false positive
- dropped the lockdep fix for up_read_non_owner in bpf_get_stackid

In addition to preempt_disable patch for socket filters
https://patchwork.ozlabs.org/patch/1032437/
First patch fixes lockdep false positive in percpu_freelist
Second patch fixes potential deadlock in bpf_prog_register
Third patch fixes another potential deadlock in stackmap access
from tracing bpf prog and from syscall.
====================
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

The map_lookup_elem used to not acquiring spinlock
in order to optimize the reader.

It was true until commit 557c0c6e ("bpf: convert stackmap to pre-allocation")
The syscall's map_lookup_elem(stackmap) calls bpf_stackmap_copy().
bpf_stackmap_copy() may find the elem no longer needed after the copy is done.
If that is the case, pcpu_freelist_push() saves this elem for reuse later.
This push requires a spinlock.

If a tracing bpf_prog got run in the middle of the syscall's
map_lookup_elem(stackmap) and this tracing bpf_prog is calling
bpf_get_stackid(stackmap) which also requires the same pcpu_freelist's
spinlock, it may end up with a dead lock situation as reported by
Eric Dumazet in https://patchwork.ozlabs.org/patch/1030266/

The situation is the same as the syscall's map_update_elem() which
needs to acquire the pcpu_freelist's spinlock and could race
with tracing bpf_prog.  Hence, this patch fixes it by protecting
bpf_stackmap_copy() with this_cpu_inc(bpf_prog_active)
to prevent tracing bpf_prog from running.

A later syscall's map_lookup_elem commit f1a2e44a ("bpf: add queue and stack maps")
also acquires a spinlock and races with tracing bpf_prog similarly.
Hence, this patch is forward looking and protects the majority
of the map lookups.  bpf_map_offload_lookup_elem() is the exception
since it is for network bpf_prog only (i.e. never called by tracing
bpf_prog).

Fixes: 557c0c6e ("bpf: convert stackmap to pre-allocation")
Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>