[ciqlts8_8-rt] writeback: avoid use-after-free after removing device

[thefossguy-ciq]

• Commit Message Requirements
• Built against Vault/LTS Environment
• kABI Check Passed, where Valid (Pre 9.4 RT does not have kABI stability)
• Boot Test
• Kernel SelfTest results
• Additional Tests as determined relevant

Commit message

jira VULN-9261
cve CVE-2024-0562
commit-author Khazhismel Kumykov <khazhy@chromium.org> commit f87904c075515f3e1d8f4a7115869d3b914674fd

When a disk is removed, bdi_unregister gets called to stop further writeback and wait for associated delayed work to complete.  However, wb_inode_writeback_end() may schedule bandwidth estimation dwork after this has completed, which can result in the timer attempting to access the just freed bdi_writeback.

Fix this by checking if the bdi_writeback is alive, similar to when scheduling writeback work.

Since this requires wb->work_lock, and wb_inode_writeback_end() may get called from interrupt, switch wb->work_lock to an irqsafe lock.

Link: https://lkml.kernel.org/r/20220801155034.3772543-1-khazhy@google.com Fixes: 45a2966fd641 ("writeback: fix bandwidth estimate for spiky workload")
	Signed-off-by: Khazhismel Kumykov <khazhy@google.com>
	Reviewed-by: Jan Kara <jack@suse.cz>
	Cc: Michael Stapelberg <stapelberg+linux@google.com>
	Cc: Wu Fengguang <fengguang.wu@intel.com>
	Cc: Alexander Viro <viro@zeniv.linux.org.uk>
	Cc: <stable@vger.kernel.org>
	Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
(cherry picked from commit f87904c075515f3e1d8f4a7115869d3b914674fd)
	Signed-off-by: Pratham Patel <ppatel@ciq.com>

Kernel build logs

  INSTALL sound/usb/snd-usbmidi-lib.ko
  INSTALL sound/usb/usx2y/snd-usb-us122l.ko
  INSTALL sound/usb/usx2y/snd-usb-usx2y.ko
  INSTALL sound/virtio/virtio_snd.ko
  INSTALL sound/x86/snd-hdmi-lpe-audio.ko
  INSTALL virt/lib/irqbypass.ko
  DEPMOD  4.18.0-_ppatel__ciqlts8_8-rt+
[TIMER]{MODULES}: 39s
Making Install
sh ./arch/x86/boot/install.sh 4.18.0-_ppatel__ciqlts8_8-rt+ arch/x86/boot/bzImage \
	System.map "/boot"
[TIMER]{INSTALL}: 11s
Setting Default Kernel to /boot/vmlinuz-4.18.0-_ppatel__ciqlts8_8-rt+ and Index to 0
Hopefully Grub2.0 took everything ... rebooting after time metrices
[TIMER]{MRPROPER}: 5s
[TIMER]{BUILD}: 1024s
[TIMER]{MODULES}: 39s
[TIMER]{INSTALL}: 11s
[TIMER]{TOTAL} 1083s
Rebooting in 10 seconds

Kselftests

$ grep '^ok ' kselftest-before.log | wc -l && grep '^ok ' kselftest-after.log | wc -l
     235
     235

$ grep '^not ok ' kselftest-before.log | wc -l && grep '^not ok ' kselftest-after.log | wc -l
      57
      57

kselftest-after.log
kselftest-before.log

[bmastbergen]

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