There are two problems in dcache_readdir() - one is that lockless traversal
of the list needs non-trivial cooperation of d_alloc() (at least a switch
to list_add_rcu(), and probably more than just that) and another is that
it assumes that no removal will happen without the directory locked exclusive.
Said assumption had always been there, never had been stated explicitly and
is violated by several places in the kernel (devpts and selinuxfs).

        * replacement of next_positive() with different calling conventions:
it returns struct list_head * instead of struct dentry *; the latter is
passed in and out by reference, grabbing the result and dropping the original
value.
        * scan is under ->d_lock.  If we run out of timeslice, cursor is moved
after the last position we'd reached and we reschedule; then the scan continues
from that place.  To avoid livelocks between multiple lseek() (with cursors
getting moved past each other, never reaching the real entries) we always
skip the cursors, need_resched() or not.
        * returned list_head * is either ->d_child of dentry we'd found or
->d_subdirs of parent (if we got to the end of the list).
        * dcache_readdir() and dcache_dir_lseek() switched to new helper.
dcache_readdir() always holds a reference to dentry passed to dir_emit() now.
Cursor is moved to just before the entry where dir_emit() has failed or into
the very end of the list, if we'd run out.
        * move_cursor() eliminated - it had sucky calling conventions and
after fixing that it became simply list_move() (in lseek and scan_positives)
or list_move_tail() (in readdir).

        All operations with the list are under ->d_lock now, and we do not
depend upon having all file removals done with parent locked exclusive
anymore.

Cc: stable@vger.kernel.org
Reported-by: "zhengbin (A)" <zhengbin13@huawei.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

This reverts commit b03755ad.

This is sad, and done for all the wrong reasons.  Because that commit is
good, and does exactly what it says: avoids a lot of small disk requests
for the inode table read-ahead.

However, it turns out that it causes an entirely unrelated problem: the
getrandom() system call was introduced back in 2014 by commit
c6e9d6f3 ("random: introduce getrandom(2) system call"), and people
use it as a convenient source of good random numbers.

But part of the current semantics for getrandom() is that it waits for
the entropy pool to fill at least partially (unlike /dev/urandom).  And
at least ArchLinux apparently has a systemd that uses getrandom() at
boot time, and the improvements in IO patterns means that existing
installations suddenly start hanging, waiting for entropy that will
never happen.

It seems to be an unlucky combination of not _quite_ enough entropy,
together with a particular systemd version and configuration.  Lennart
says that the systemd-random-seed process (which is what does this early
access) is supposed to not block any other boot activity, but sadly that
doesn't actually seem to be the case (possibly due bogus dependencies on
cryptsetup for encrypted swapspace).

The correct fix is to fix getrandom() to not block when it's not
appropriate, but that fix is going to take a lot more discussion.  Do we
just make it act like /dev/urandom by default, and add a new flag for
"wait for entropy"? Do we add a boot-time option? Or do we just limit
the amount of time it will wait for entropy?

So in the meantime, we do the revert to give us time to discuss the
eventual fix for the fundamental problem, at which point we can re-apply
the ext4 inode table access optimization.
Reported-by: Ahmed S. Darwish <darwish.07@gmail.com>
Cc: Ted Ts'o <tytso@mit.edu>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Alexander E. Patrakov <patrakov@gmail.com>
Cc: Lennart Poettering <mzxreary@0pointer.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull kvm fixes from Paolo Bonzini:
 "The main change here is a revert of reverts. We recently simplified
  some code that was thought unnecessary; however, since then KVM has
  grown quite a few cond_resched()s and for that reason the simplified
  code is prone to livelocks---one CPUs tries to empty a list of guest
  page tables while the others keep adding to them. This adds back the
  generation-based zapping of guest page tables, which was not
  unnecessary after all.

  On top of this, there is a fix for a kernel memory leak and a couple
  of s390 fixlets as well"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: x86/mmu: Reintroduce fast invalidate/zap for flushing memslot
  KVM: x86: work around leak of uninitialized stack contents
  KVM: nVMX: handle page fault in vmread
  KVM: s390: Do not leak kernel stack data in the KVM_S390_INTERRUPT ioctl
  KVM: s390: kvm_s390_vm_start_migration: check dirty_bitmap before using it as target for memset()

Pull virtio fix from Michael Tsirkin:
 "A last minute revert

  The 32-bit build got broken by the latest defence in depth patch.
  Revert and we'll try again in the next cycle"

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
  Revert "vhost: block speculation of translated descriptors"

Pull RISC-V fix from Paul Walmsley:
 "Last week, Palmer and I learned that there was an error in the RISC-V
  kernel image header format that could make it less compatible with the
  ARM64 kernel image header format. I had missed this error during my
  original reviews of the patch.

  The kernel image header format is an interface that impacts
  bootloaders, QEMU, and other user tools. Those packages must be
  updated to align with whatever is merged in the kernel. We would like
  to avoid proliferating these image formats by keeping the RISC-V
  header as close as possible to the existing ARM64 header. Since the
  arch/riscv patch that adds support for the image header was merged
  with our v5.3-rc1 pull request as commit 0f327f2a ("RISC-V: Add
  an Image header that boot loader can parse."), we think it wise to try
  to fix this error before v5.3 is released.

  The fix itself should be backwards-compatible with any project that
  has already merged support for premature versions of this interface.
  It primarily involves ensuring that the RISC-V image header has
  something useful in the same field as the ARM64 image header"

* tag 'riscv/for-v5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  riscv: modify the Image header to improve compatibility with the ARM64 header

This reverts commit a89db445.

I was hasty to include this patch, and it breaks the build on 32 bit.
Defence in depth is good but let's do it properly.

Cc: stable@vger.kernel.org
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Pull networking fixes from David Miller:

 1) Don't corrupt xfrm_interface parms before validation, from Nicolas
    Dichtel.

 2) Revert use of usb-wakeup in btusb, from Mario Limonciello.

 3) Block ipv6 packets in bridge netfilter if ipv6 is disabled, from
    Leonardo Bras.

 4) IPS_OFFLOAD not honored in ctnetlink, from Pablo Neira Ayuso.

 5) Missing ULP check in sock_map, from John Fastabend.

 6) Fix receive statistic handling in forcedeth, from Zhu Yanjun.

 7) Fix length of SKB allocated in 6pack driver, from Christophe
    JAILLET.

 8) ip6_route_info_create() returns an error pointer, not NULL. From
    Maciej Żenczykowski.

 9) Only add RDS sock to the hashes after rs_transport is set, from
    Ka-Cheong Poon.

10) Don't double clean TX descriptors in ixgbe, from Ilya Maximets.

11) Presence of transmit IPSEC offload in an SKB is not tested for
    correctly in ixgbe and ixgbevf. From Steffen Klassert and Jeff
    Kirsher.

12) Need rcu_barrier() when register_netdevice() takes one of the
    notifier based failure paths, from Subash Abhinov Kasiviswanathan.

13) Fix leak in sctp_do_bind(), from Mao Wenan.

* git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (72 commits)
  cdc_ether: fix rndis support for Mediatek based smartphones
  sctp: destroy bucket if failed to bind addr
  sctp: remove redundant assignment when call sctp_get_port_local
  sctp: change return type of sctp_get_port_local
  ixgbevf: Fix secpath usage for IPsec Tx offload
  sctp: Fix the link time qualifier of 'sctp_ctrlsock_exit()'
  ixgbe: Fix secpath usage for IPsec TX offload.
  net: qrtr: fix memort leak in qrtr_tun_write_iter
  net: Fix null de-reference of device refcount
  ipv6: Fix the link time qualifier of 'ping_v6_proc_exit_net()'
  tun: fix use-after-free when register netdev failed
  tcp: fix tcp_ecn_withdraw_cwr() to clear TCP_ECN_QUEUE_CWR
  ixgbe: fix double clean of Tx descriptors with xdp
  ixgbe: Prevent u8 wrapping of ITR value to something less than 10us
  mlx4: fix spelling mistake "veify" -> "verify"
  net: hns3: fix spelling mistake "undeflow" -> "underflow"
  net: lmc: fix spelling mistake "runnin" -> "running"
  NFC: st95hf: fix spelling mistake "receieve" -> "receive"
  net/rds: An rds_sock is added too early to the hash table
  mac80211: Do not send Layer 2 Update frame before authorization
  ...

Pull MMC fixes from Ulf Hansson:

 - tmio: Fixup runtime PM management during probe and remove

 - sdhci-pci-o2micro: Fix eMMC initialization for an AMD SoC

 - bcm2835: Prevent lockups when terminating work

* tag 'mmc-v5.3-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc:
  mmc: tmio: Fixup runtime PM management during remove
  mmc: tmio: Fixup runtime PM management during probe
  Revert "mmc: tmio: move runtime PM enablement to the driver implementations"
  Revert "mmc: sdhci: Remove unneeded quirk2 flag of O2 SD host controller"
  Revert "mmc: bcm2835: Terminate timeout work synchronously"

Pull drm fixes from Dave Airlie:
 "From the maintainer summit, just some last minute fixes for final:

  lima:
   - fix gem_wait ioctl

  core:
   - constify modes list

  i915:
   - DP MST high color depth regression
   - GPU hangs on vulkan compute workloads"

* tag 'drm-fixes-2019-09-13' of git://anongit.freedesktop.org/drm/drm:
  drm/lima: fix lima_gem_wait() return value
  drm/i915: Restore relaxed padding (OCL_OOB_SUPPRES_ENABLE) for skl+
  drm/i915: Limit MST to <= 8bpc once again
  drm/modes: Make the whitelist more const

Merge tag 'kvm-s390-master-5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into kvm-master

KVM: s390: Fixes for 5.3

- prevent a user triggerable oops in the migration code
- do not leak kernel stack content

James Harvey reported a livelock that was introduced by commit
d012a06a ("Revert "KVM: x86/mmu: Zap only the relevant pages when
removing a memslot"").

The livelock occurs because kvm_mmu_zap_all() as it exists today will
voluntarily reschedule and drop KVM's mmu_lock, which allows other vCPUs
to add shadow pages.  With enough vCPUs, kvm_mmu_zap_all() can get stuck
in an infinite loop as it can never zap all pages before observing lock
contention or the need to reschedule.  The equivalent of kvm_mmu_zap_all()
that was in use at the time of the reverted commit (4e103134, "KVM:
x86/mmu: Zap only the relevant pages when removing a memslot") employed
a fast invalidate mechanism and was not susceptible to the above livelock.

There are three ways to fix the livelock:

- Reverting the revert (commit d012a06a) is not a viable option as
  the revert is needed to fix a regression that occurs when the guest has
  one or more assigned devices.  It's unlikely we'll root cause the device
  assignment regression soon enough to fix the regression timely.

- Remove the conditional reschedule from kvm_mmu_zap_all().  However, although
  removing the reschedule would be a smaller code change, it's less safe
  in the sense that the resulting kvm_mmu_zap_all() hasn't been used in
  the wild for flushing memslots since the fast invalidate mechanism was
  introduced by commit 6ca18b69 ("KVM: x86: use the fast way to
  invalidate all pages"), back in 2013.

- Reintroduce the fast invalidate mechanism and use it when zapping shadow
  pages in response to a memslot being deleted/moved, which is what this
  patch does.

For all intents and purposes, this is a revert of commit ea145aac
("Revert "KVM: MMU: fast invalidate all pages"") and a partial revert of
commit 7390de1e ("Revert "KVM: x86: use the fast way to invalidate
all pages""), i.e. restores the behavior of commit 5304b8d3 ("KVM:
MMU: fast invalidate all pages") and commit 6ca18b69 ("KVM: x86:
use the fast way to invalidate all pages") respectively.

Fixes: d012a06a ("Revert "KVM: x86/mmu: Zap only the relevant pages when removing a memslot"")
Reported-by: James Harvey <jamespharvey20@gmail.com>
Cc: Alex Willamson <alex.williamson@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Emulation of VMPTRST can incorrectly inject a page fault
when passed an operand that points to an MMIO address.
The page fault will use uninitialized kernel stack memory
as the CR2 and error code.

The right behavior would be to abort the VM with a KVM_EXIT_INTERNAL_ERROR
exit to userspace; however, it is not an easy fix, so for now just ensure
that the error code and CR2 are zero.
Signed-off-by: Fuqian Huang <huangfq.daxian@gmail.com>
Cc: stable@vger.kernel.org
[add comment]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

The implementation of vmread to memory is still incomplete, as it
lacks the ability to do vmread to I/O memory just like vmptrst.

Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Part of the intention during the definition of the RISC-V kernel image
header was to lay the groundwork for a future merge with the ARM64
image header.  One error during my original review was not noticing
that the RISC-V header's "magic" field was at a different size and
position than the ARM64's "magic" field.  If the existing ARM64 Image
header parsing code were to attempt to parse an existing RISC-V kernel
image header format, it would see a magic number 0.  This is
undesirable, since it's our intention to align as closely as possible
with the ARM64 header format.  Another problem was that the original
"res3" field was not being initialized correctly to zero.

Address these issues by creating a 32-bit "magic2" field in the RISC-V
header which matches the ARM64 "magic" field.  RISC-V binaries will
store "RSC\x05" in this field.  The intention is that the use of the
existing 64-bit "magic" field in the RISC-V header will be deprecated
over time.  Increment the minor version number of the file format to
indicate this change, and update the documentation accordingly.  Fix
the assembler directives in head.S to ensure that reserved fields are
properly zero-initialized.
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
Reported-by: Palmer Dabbelt <palmer@sifive.com>
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
Cc: Atish Patra <atish.patra@wdc.com>
Cc: Karsten Merker <merker@debian.org>
Link: https://lore.kernel.org/linux-riscv/194c2f10c9806720623430dbf0cc59a965e50448.camel@wdc.com/T/#u
Link: https://lore.kernel.org/linux-riscv/mhng-755b14c4-8f35-4079-a7ff-e421fd1b02bc@palmer-si-x1e/T/#t

A Mediatek based smartphone owner reports problems with USB
tethering in Linux.  The verbose USB listing shows a rndis_host
interface pair (e0/01/03 + 10/00/00), but the driver fails to
bind with

[  355.960428] usb 1-4: bad CDC descriptors

The problem is a failsafe test intended to filter out ACM serial
functions using the same 02/02/ff class/subclass/protocol as RNDIS.
The serial functions are recognized by their non-zero bmCapabilities.

No RNDIS function with non-zero bmCapabilities were known at the time
this failsafe was added. But it turns out that some Wireless class
RNDIS functions are using the bmCapabilities field. These functions
are uniquely identified as RNDIS by their class/subclass/protocol, so
the failing test can safely be disabled.  The same applies to the two
types of Misc class RNDIS functions.

Applying the failsafe to Communication class functions only retains
the original functionality, and fixes the problem for the Mediatek based
smartphone.

Tow examples of CDC functional descriptors with non-zero bmCapabilities
from Wireless class RNDIS functions are:

0e8d:000a  Mediatek Crosscall Spider X5 3G Phone

      CDC Header:
        bcdCDC               1.10
      CDC ACM:
        bmCapabilities       0x0f
          connection notifications
          sends break
          line coding and serial state
          get/set/clear comm features
      CDC Union:
        bMasterInterface        0
        bSlaveInterface         1
      CDC Call Management:
        bmCapabilities       0x03
          call management
          use DataInterface
        bDataInterface          1

and

19d2:1023  ZTE K4201-z

      CDC Header:
        bcdCDC               1.10
      CDC ACM:
        bmCapabilities       0x02
          line coding and serial state
      CDC Call Management:
        bmCapabilities       0x03
          call management
          use DataInterface
        bDataInterface          1
      CDC Union:
        bMasterInterface        0
        bSlaveInterface         1

The Mediatek example is believed to apply to most smartphones with
Mediatek firmware.  The ZTE example is most likely also part of a larger
family of devices/firmwares.
Suggested-by: Lars Melin <larsm17@gmail.com>
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: David S. Miller <davem@davemloft.net>

Mao Wenan says:

====================
fix memory leak for sctp_do_bind

First two patches are to do cleanup, remove redundant assignment,
and change return type of sctp_get_port_local.
Third patch is to fix memory leak for sctp_do_bind if failed
to bind address.

v2: add one patch to change return type of sctp_get_port_local.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

There is one memory leak bug report:
BUG: memory leak
unreferenced object 0xffff8881dc4c5ec0 (size 40):
  comm "syz-executor.0", pid 5673, jiffies 4298198457 (age 27.578s)
  hex dump (first 32 bytes):
    02 00 00 00 81 88 ff ff 00 00 00 00 00 00 00 00  ................
    f8 63 3d c1 81 88 ff ff 00 00 00 00 00 00 00 00  .c=.............
  backtrace:
    [<0000000072006339>] sctp_get_port_local+0x2a1/0xa00 [sctp]
    [<00000000c7b379ec>] sctp_do_bind+0x176/0x2c0 [sctp]
    [<000000005be274a2>] sctp_bind+0x5a/0x80 [sctp]
    [<00000000b66b4044>] inet6_bind+0x59/0xd0 [ipv6]
    [<00000000c68c7f42>] __sys_bind+0x120/0x1f0 net/socket.c:1647
    [<000000004513635b>] __do_sys_bind net/socket.c:1658 [inline]
    [<000000004513635b>] __se_sys_bind net/socket.c:1656 [inline]
    [<000000004513635b>] __x64_sys_bind+0x3e/0x50 net/socket.c:1656
    [<0000000061f2501e>] do_syscall_64+0x72/0x2e0 arch/x86/entry/common.c:296
    [<0000000003d1e05e>] entry_SYSCALL_64_after_hwframe+0x49/0xbe

This is because in sctp_do_bind, if sctp_get_port_local is to
create hash bucket successfully, and sctp_add_bind_addr failed
to bind address, e.g return -ENOMEM, so memory leak found, it
needs to destroy allocated bucket.
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Mao Wenan <maowenan@huawei.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

There are more parentheses in if clause when call sctp_get_port_local
in sctp_do_bind, and redundant assignment to 'ret'. This patch is to
do cleanup.
Signed-off-by: Mao Wenan <maowenan@huawei.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Currently sctp_get_port_local() returns a long
which is either 0,1 or a pointer casted to long.
It's neither of the callers use the return value since
commit 62208f12 ("net: sctp: simplify sctp_get_port").
Now two callers are sctp_get_port and sctp_do_bind,
they actually assumend a casted to an int was the same as
a pointer casted to a long, and they don't save the return
value just check whether it is zero or non-zero, so
it would better change return type from long to int for
sctp_get_port_local.
Signed-off-by: Mao Wenan <maowenan@huawei.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Port the same fix for ixgbe to ixgbevf.

The ixgbevf driver currently does IPsec Tx offloading
based on an existing secpath. However, the secpath
can also come from the Rx side, in this case it is
misinterpreted for Tx offload and the packets are
dropped with a "bad sa_idx" error. Fix this by using
the xfrm_offload() function to test for Tx offload.

CC: Shannon Nelson <snelson@pensando.io>
Fixes: 7f68d430 ("ixgbevf: enable VF IPsec offload operations")
Reported-by: Jonathan Tooker <jonathan@reliablehosting.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Acked-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>

Accessing the device when it may be runtime suspended is a bug, which is
the case in tmio_mmc_host_remove(). Let's fix the behaviour.

Cc: stable@vger.kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>

The tmio_mmc_host_probe() calls pm_runtime_set_active() to update the
runtime PM status of the device, as to make it reflect the current status
of the HW. This works fine for most cases, but unfortunate not for all.
Especially, there is a generic problem when the device has a genpd attached
and that genpd have the ->start|stop() callbacks assigned.

More precisely, if the driver calls pm_runtime_set_active() during
->probe(), genpd does not get to invoke the ->start() callback for it,
which means the HW isn't really fully powered on. Furthermore, in the next
phase, when the device becomes runtime suspended, genpd will invoke the
->stop() callback for it, potentially leading to usage count imbalance
problems, depending on what's implemented behind the callbacks of course.

To fix this problem, convert to call pm_runtime_get_sync() from
tmio_mmc_host_probe() rather than pm_runtime_set_active(). Additionally, to
avoid bumping usage counters and unnecessary re-initializing the HW the
first time the tmio driver's ->runtime_resume() callback is called,
introduce a state flag to keeping track of this.

Cc: stable@vger.kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>

This reverts commit 7ff21319.

It turns out that the above commit introduces other problems. For example,
calling pm_runtime_set_active() must not be done prior calling
pm_runtime_enable() as that makes it fail. This leads to additional
problems, such as clock enables being wrongly balanced.

Rather than fixing the problem on top, let's start over by doing a revert.

Fixes: 7ff21319 ("mmc: tmio: move runtime PM enablement to the driver implementations")
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>

Pull cgroup fix from Tejun Heo:
 "Roman found and fixed a bug in the cgroup2 freezer which allows new
  child cgroup to escape frozen state"

* 'for-5.3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: freezer: fix frozen state inheritance
  kselftests: cgroup: add freezer mkdir test

Pull btrfs fixes from David Sterba:
 "Here are two fixes, one of them urgent fixing a bug introduced in 5.2
  and reported by many users. It took time to identify the root cause,
  catching the 5.3 release is higly desired also to push the fix to 5.2
  stable tree.

  The bug is a mess up of return values after adding proper error
  handling and honestly the kind of bug that can cause sleeping
  disorders until it's caught. My appologies to everybody who was
  affected.

  Summary of what could happen:

  1) either a hang when committing a transaction, if this happens
     there's no risk of corruption, still the hang is very inconvenient
     and can't be resolved without a reboot

  2) writeback for some btree nodes may never be started and we end up
     committing a transaction without noticing that, this is really
     serious and that will lead to the "parent transid verify failed"
     messages"

* tag 'for-5.3-rc8-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  Btrfs: fix unwritten extent buffers and hangs on future writeback attempts
  Btrfs: fix assertion failure during fsync and use of stale transaction

If a new child cgroup is created in the frozen cgroup hierarchy
(one or more of ancestor cgroups is frozen), the CGRP_FREEZE cgroup
flag should be set. Otherwise if a process will be attached to the
child cgroup, it won't become frozen.

The problem can be reproduced with the test_cgfreezer_mkdir test.

This is the output before this patch:
  ~/test_freezer
  ok 1 test_cgfreezer_simple
  ok 2 test_cgfreezer_tree
  ok 3 test_cgfreezer_forkbomb
  Cgroup /sys/fs/cgroup/cg_test_mkdir_A/cg_test_mkdir_B isn't frozen
  not ok 4 test_cgfreezer_mkdir
  ok 5 test_cgfreezer_rmdir
  ok 6 test_cgfreezer_migrate
  ok 7 test_cgfreezer_ptrace
  ok 8 test_cgfreezer_stopped
  ok 9 test_cgfreezer_ptraced
  ok 10 test_cgfreezer_vfork

And with this patch:
  ~/test_freezer
  ok 1 test_cgfreezer_simple
  ok 2 test_cgfreezer_tree
  ok 3 test_cgfreezer_forkbomb
  ok 4 test_cgfreezer_mkdir
  ok 5 test_cgfreezer_rmdir
  ok 6 test_cgfreezer_migrate
  ok 7 test_cgfreezer_ptrace
  ok 8 test_cgfreezer_stopped
  ok 9 test_cgfreezer_ptraced
  ok 10 test_cgfreezer_vfork
Reported-by: Mark Crossen <mcrossen@fb.com>
Signed-off-by: Roman Gushchin <guro@fb.com>
Fixes: 76f969e8 ("cgroup: cgroup v2 freezer")
Cc: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org # v5.2+
Signed-off-by: Tejun Heo <tj@kernel.org>

Add a new cgroup freezer selftest, which checks that if a cgroup is
frozen, their new child cgroups will properly inherit the frozen
state.

It creates a parent cgroup, freezes it, creates a child cgroup
and populates it with a dummy process. Then it checks that both
parent and child cgroup are frozen.
Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>

The userptr put_pages can be called from inside try_to_unmap, and so
enters with the page lock held on one of the object's backing pages. We
cannot take the page lock ourselves for fear of recursion.
Reported-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reported-by: Martin Wilck <Martin.Wilck@suse.com>
Reported-by: Leo Kraav <leho@kraav.com>
Fixes: aa56a292 ("drm/i915/userptr: Acquire the page lock around set_page_dirty()")
References: https://bugzilla.kernel.org/show_bug.cgi?id=203317Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull clone3 fix from Christian Brauner:
 "This is a last-minute bugfix for clone3() that should go in before we
  release 5.3 with clone3().

  clone3() did not verify that the exit_signal argument was set to a
  valid signal. This can be used to cause a crash by specifying a signal
  greater than NSIG. e.g. -1.

  The commit from Eugene adds a check to copy_clone_args_from_user() to
  verify that the exit signal is limited by CSIGNAL as with legacy
  clone() and that the signal is valid. With this we don't get the
  legacy clone behavior were an invalid signal could be handed down and
  would only be detected and then ignored in do_notify_parent(). Users
  of clone3() will now get a proper error right when they pass an
  invalid exit signal. Note, that this is not a change in user-visible
  behavior since no kernel with clone3() has been released yet"

* tag 'for-linus-20190912' of gitolite.kernel.org:pub/scm/linux/kernel/git/brauner/linux:
  fork: block invalid exit signals with clone3()

Pull x86 fixes from Ingo Molnar:
 "A KVM guest fix, and a kdump kernel relocation errors fix"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/timer: Force PIT initialization when !X86_FEATURE_ARAT
  x86/purgatory: Change compiler flags from -mcmodel=kernel to -mcmodel=large to fix kexec relocation errors

drm-misc-fixes for v5.3 final:
- Constify modes whitelist harder.
- Fix lima driver gem_wait ioctl.
Signed-off-by: Dave Airlie <airlied@redhat.com>

From: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/99e52e7a-d4ce-6a2c-0501-bc559a710955@linux.intel.com

Merge tag 'drm-intel-fixes-2019-09-11' of git://anongit.freedesktop.org/drm/drm-intel into drm-fixes

Final drm/i915 fixes for v5.3:
- Fox DP MST high color depth regression
- Fix GPU hangs on Vulkan compute workloads
Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/877e6e27qm.fsf@intel.com

Previously, higher 32 bits of exit_signal fields were lost when copied
to the kernel args structure (that uses int as a type for the respective
field). Moreover, as Oleg has noted, exit_signal is used unchecked, so
it has to be checked for sanity before use; for the legacy syscalls,
applying CSIGNAL mask guarantees that it is at least non-negative;
however, there's no such thing is done in clone3() code path, and that
can break at least thread_group_leader.

This commit adds a check to copy_clone_args_from_user() to verify that
the exit signal is limited by CSIGNAL as with legacy clone() and that
the signal is valid. With this we don't get the legacy clone behavior
were an invalid signal could be handed down and would only be detected
and ignored in do_notify_parent(). Users of clone3() will now get a
proper error when they pass an invalid exit signal. Note, that this is
not user-visible behavior since no kernel with clone3() has been
released yet.

The following program will cause a splat on a non-fixed clone3() version
and will fail correctly on a fixed version:

 #define _GNU_SOURCE
 #include <linux/sched.h>
 #include <linux/types.h>
 #include <sched.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/syscall.h>
 #include <sys/wait.h>
 #include <unistd.h>

 int main(int argc, char *argv[])
 {
        pid_t pid = -1;
        struct clone_args args = {0};
        args.exit_signal = -1;

        pid = syscall(__NR_clone3, &args, sizeof(struct clone_args));
        if (pid < 0)
                exit(EXIT_FAILURE);

        if (pid == 0)
                exit(EXIT_SUCCESS);

        wait(NULL);

        exit(EXIT_SUCCESS);
 }

Fixes: 7f192e3c ("fork: add clone3")
Reported-by: Oleg Nesterov <oleg@redhat.com>
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Suggested-by: Dmitry V. Levin <ldv@altlinux.org>
Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com>
Link: https://lore.kernel.org/r/4b38fa4ce420b119a4c6345f42fe3cec2de9b0b5.1568223594.git.esyr@redhat.com
[christian.brauner@ubuntu.com: simplify check and rework commit message]
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

When the userspace program runs the KVM_S390_INTERRUPT ioctl to inject
an interrupt, we convert them from the legacy struct kvm_s390_interrupt
to the new struct kvm_s390_irq via the s390int_to_s390irq() function.
However, this function does not take care of all types of interrupts
that we can inject into the guest later (see do_inject_vcpu()). Since we
do not clear out the s390irq values before calling s390int_to_s390irq(),
there is a chance that we copy random data from the kernel stack which
could be leaked to the userspace later.

Specifically, the problem exists with the KVM_S390_INT_PFAULT_INIT
interrupt: s390int_to_s390irq() does not handle it, and the function
__inject_pfault_init() later copies irq->u.ext which contains the
random kernel stack data. This data can then be leaked either to
the guest memory in __deliver_pfault_init(), or the userspace might
retrieve it directly with the KVM_S390_GET_IRQ_STATE ioctl.

Fix it by handling that interrupt type in s390int_to_s390irq(), too,
and by making sure that the s390irq struct is properly pre-initialized.
And while we're at it, make sure that s390int_to_s390irq() now
directly returns -EINVAL for unknown interrupt types, so that we
immediately get a proper error code in case we add more interrupt
types to do_inject_vcpu() without updating s390int_to_s390irq()
sometime in the future.

Cc: stable@vger.kernel.org
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Link: https://lore.kernel.org/kvm/20190912115438.25761-1-thuth@redhat.comSigned-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

The '.exit' functions from 'pernet_operations' structure should be marked
as __net_exit, not __net_init.

Fixes: 8e2d61e0 ("sctp: fix race on protocol/netns initialization")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The ixgbe driver currently does IPsec TX offloading
based on an existing secpath. However, the secpath
can also come from the RX side, in this case it is
misinterpreted for TX offload and the packets are
dropped with a "bad sa_idx" error. Fix this by using
the xfrm_offload() function to test for TX offload.

Fixes: 59259470 ("ixgbe: process the Tx ipsec offload")
Reported-by: Michael Marley <michael@michaelmarley.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The lock_extent_buffer_io() returns 1 to the caller to tell it everything
went fine and the callers needs to start writeback for the extent buffer
(submit a bio, etc), 0 to tell the caller everything went fine but it does
not need to start writeback for the extent buffer, and a negative value if
some error happened.

When it's about to return 1 it tries to lock all pages, and if a try lock
on a page fails, and we didn't flush any existing bio in our "epd", it
calls flush_write_bio(epd) and overwrites the return value of 1 to 0 or
an error. The page might have been locked elsewhere, not with the goal
of starting writeback of the extent buffer, and even by some code other
than btrfs, like page migration for example, so it does not mean the
writeback of the extent buffer was already started by some other task,
so returning a 0 tells the caller (btree_write_cache_pages()) to not
start writeback for the extent buffer. Note that epd might currently have
either no bio, so flush_write_bio() returns 0 (success) or it might have
a bio for another extent buffer with a lower index (logical address).

Since we return 0 with the EXTENT_BUFFER_WRITEBACK bit set on the
extent buffer and writeback is never started for the extent buffer,
future attempts to writeback the extent buffer will hang forever waiting
on that bit to be cleared, since it can only be cleared after writeback
completes. Such hang is reported with a trace like the following:

  [49887.347053] INFO: task btrfs-transacti:1752 blocked for more than 122 seconds.
  [49887.347059]       Not tainted 5.2.13-gentoo #2
  [49887.347060] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  [49887.347062] btrfs-transacti D    0  1752      2 0x80004000
  [49887.347064] Call Trace:
  [49887.347069]  ? __schedule+0x265/0x830
  [49887.347071]  ? bit_wait+0x50/0x50
  [49887.347072]  ? bit_wait+0x50/0x50
  [49887.347074]  schedule+0x24/0x90
  [49887.347075]  io_schedule+0x3c/0x60
  [49887.347077]  bit_wait_io+0x8/0x50
  [49887.347079]  __wait_on_bit+0x6c/0x80
  [49887.347081]  ? __lock_release.isra.29+0x155/0x2d0
  [49887.347083]  out_of_line_wait_on_bit+0x7b/0x80
  [49887.347084]  ? var_wake_function+0x20/0x20
  [49887.347087]  lock_extent_buffer_for_io+0x28c/0x390
  [49887.347089]  btree_write_cache_pages+0x18e/0x340
  [49887.347091]  do_writepages+0x29/0xb0
  [49887.347093]  ? kmem_cache_free+0x132/0x160
  [49887.347095]  ? convert_extent_bit+0x544/0x680
  [49887.347097]  filemap_fdatawrite_range+0x70/0x90
  [49887.347099]  btrfs_write_marked_extents+0x53/0x120
  [49887.347100]  btrfs_write_and_wait_transaction.isra.4+0x38/0xa0
  [49887.347102]  btrfs_commit_transaction+0x6bb/0x990
  [49887.347103]  ? start_transaction+0x33e/0x500
  [49887.347105]  transaction_kthread+0x139/0x15c

So fix this by not overwriting the return value (ret) with the result
from flush_write_bio(). We also need to clear the EXTENT_BUFFER_WRITEBACK
bit in case flush_write_bio() returns an error, otherwise it will hang
any future attempts to writeback the extent buffer, and undo all work
done before (set back EXTENT_BUFFER_DIRTY, etc).

This is a regression introduced in the 5.2 kernel.

Fixes: 2e3c2513 ("btrfs: extent_io: add proper error handling to lock_extent_buffer_for_io()")
Fixes: f4340622 ("btrfs: extent_io: Move the BUG_ON() in flush_write_bio() one level up")
Reported-by: Zdenek Sojka <zsojka@seznam.cz>
Link: https://lore.kernel.org/linux-btrfs/GpO.2yos.3WGDOLpx6t%7D.1TUDYM@seznam.cz/T/#uReported-by: Stefan Priebe - Profihost AG <s.priebe@profihost.ag>
Link: https://lore.kernel.org/linux-btrfs/5c4688ac-10a7-fb07-70e8-c5d31a3fbb38@profihost.ag/T/#tReported-by: Drazen Kacar <drazen.kacar@oradian.com>
Link: https://lore.kernel.org/linux-btrfs/DB8PR03MB562876ECE2319B3E579590F799C80@DB8PR03MB5628.eurprd03.prod.outlook.com/
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=204377Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Sometimes when fsync'ing a file we need to log that other inodes exist and
when we need to do that we acquire a reference on the inodes and then drop
that reference using iput() after logging them.

That generally is not a problem except if we end up doing the final iput()
(dropping the last reference) on the inode and that inode has a link count
of 0, which can happen in a very short time window if the logging path
gets a reference on the inode while it's being unlinked.

In that case we end up getting the eviction callback, btrfs_evict_inode(),
invoked through the iput() call chain which needs to drop all of the
inode's items from its subvolume btree, and in order to do that, it needs
to join a transaction at the helper function evict_refill_and_join().
However because the task previously started a transaction at the fsync
handler, btrfs_sync_file(), it has current->journal_info already pointing
to a transaction handle and therefore evict_refill_and_join() will get
that transaction handle from btrfs_join_transaction(). From this point on,
two different problems can happen:

1) evict_refill_and_join() will often change the transaction handle's
   block reserve (->block_rsv) and set its ->bytes_reserved field to a
   value greater than 0. If evict_refill_and_join() never commits the
   transaction, the eviction handler ends up decreasing the reference
   count (->use_count) of the transaction handle through the call to
   btrfs_end_transaction(), and after that point we have a transaction
   handle with a NULL ->block_rsv (which is the value prior to the
   transaction join from evict_refill_and_join()) and a ->bytes_reserved
   value greater than 0. If after the eviction/iput completes the inode
   logging path hits an error or it decides that it must fallback to a
   transaction commit, the btrfs fsync handle, btrfs_sync_file(), gets a
   non-zero value from btrfs_log_dentry_safe(), and because of that
   non-zero value it tries to commit the transaction using a handle with
   a NULL ->block_rsv and a non-zero ->bytes_reserved value. This makes
   the transaction commit hit an assertion failure at
   btrfs_trans_release_metadata() because ->bytes_reserved is not zero but
   the ->block_rsv is NULL. The produced stack trace for that is like the
   following:

   [192922.917158] assertion failed: !trans->bytes_reserved, file: fs/btrfs/transaction.c, line: 816
   [192922.917553] ------------[ cut here ]------------
   [192922.917922] kernel BUG at fs/btrfs/ctree.h:3532!
   [192922.918310] invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC PTI
   [192922.918666] CPU: 2 PID: 883 Comm: fsstress Tainted: G        W         5.1.4-btrfs-next-47 #1
   [192922.919035] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.2-0-gf9626ccb91-prebuilt.qemu-project.org 04/01/2014
   [192922.919801] RIP: 0010:assfail.constprop.25+0x18/0x1a [btrfs]
   (...)
   [192922.920925] RSP: 0018:ffffaebdc8a27da8 EFLAGS: 00010286
   [192922.921315] RAX: 0000000000000051 RBX: ffff95c9c16a41c0 RCX: 0000000000000000
   [192922.921692] RDX: 0000000000000000 RSI: ffff95cab6b16838 RDI: ffff95cab6b16838
   [192922.922066] RBP: ffff95c9c16a41c0 R08: 0000000000000000 R09: 0000000000000000
   [192922.922442] R10: ffffaebdc8a27e70 R11: 0000000000000000 R12: ffff95ca731a0980
   [192922.922820] R13: 0000000000000000 R14: ffff95ca84c73338 R15: ffff95ca731a0ea8
   [192922.923200] FS:  00007f337eda4e80(0000) GS:ffff95cab6b00000(0000) knlGS:0000000000000000
   [192922.923579] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
   [192922.923948] CR2: 00007f337edad000 CR3: 00000001e00f6002 CR4: 00000000003606e0
   [192922.924329] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
   [192922.924711] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
   [192922.925105] Call Trace:
   [192922.925505]  btrfs_trans_release_metadata+0x10c/0x170 [btrfs]
   [192922.925911]  btrfs_commit_transaction+0x3e/0xaf0 [btrfs]
   [192922.926324]  btrfs_sync_file+0x44c/0x490 [btrfs]
   [192922.926731]  do_fsync+0x38/0x60
   [192922.927138]  __x64_sys_fdatasync+0x13/0x20
   [192922.927543]  do_syscall_64+0x60/0x1c0
   [192922.927939]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
   (...)
   [192922.934077] ---[ end trace f00808b12068168f ]---

2) If evict_refill_and_join() decides to commit the transaction, it will
   be able to do it, since the nested transaction join only increments the
   transaction handle's ->use_count reference counter and it does not
   prevent the transaction from getting committed. This means that after
   eviction completes, the fsync logging path will be using a transaction
   handle that refers to an already committed transaction. What happens
   when using such a stale transaction can be unpredictable, we are at
   least having a use-after-free on the transaction handle itself, since
   the transaction commit will call kmem_cache_free() against the handle
   regardless of its ->use_count value, or we can end up silently losing
   all the updates to the log tree after that iput() in the logging path,
   or using a transaction handle that in the meanwhile was allocated to
   another task for a new transaction, etc, pretty much unpredictable
   what can happen.

In order to fix both of them, instead of using iput() during logging, use
btrfs_add_delayed_iput(), so that the logging path of fsync never drops
the last reference on an inode, that step is offloaded to a safe context
(usually the cleaner kthread).

The assertion failure issue was sporadically triggered by the test case
generic/475 from fstests, which loads the dm error target while fsstress
is running, which lead to fsync failing while logging inodes with -EIO
errors and then trying later to commit the transaction, triggering the
assertion failure.

CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

If userspace doesn't set KVM_MEM_LOG_DIRTY_PAGES on memslot before calling
kvm_s390_vm_start_migration(), kernel will oops with:

  Unable to handle kernel pointer dereference in virtual kernel address space
  Failing address: 0000000000000000 TEID: 0000000000000483
  Fault in home space mode while using kernel ASCE.
  AS:0000000002a2000b R2:00000001bff8c00b R3:00000001bff88007 S:00000001bff91000 P:000000000000003d
  Oops: 0004 ilc:2 [#1] SMP
  ...
  Call Trace:
  ([<001fffff804ec552>] kvm_s390_vm_set_attr+0x347a/0x3828 [kvm])
   [<001fffff804ecfc0>] kvm_arch_vm_ioctl+0x6c0/0x1998 [kvm]
   [<001fffff804b67e4>] kvm_vm_ioctl+0x51c/0x11a8 [kvm]
   [<00000000008ba572>] do_vfs_ioctl+0x1d2/0xe58
   [<00000000008bb284>] ksys_ioctl+0x8c/0xb8
   [<00000000008bb2e2>] sys_ioctl+0x32/0x40
   [<000000000175552c>] system_call+0x2b8/0x2d8
  INFO: lockdep is turned off.
  Last Breaking-Event-Address:
   [<0000000000dbaf60>] __memset+0xc/0xa0

due to ms->dirty_bitmap being NULL, which might crash the host.

Make sure that ms->dirty_bitmap is set before using it or
return -EINVAL otherwise.

Cc: <stable@vger.kernel.org>
Fixes: afdad616 ("KVM: s390: Fix storage attributes migration with memory slots")
Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Link: https://lore.kernel.org/kvm/20190911075218.29153-1-imammedo@redhat.com/Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>