Subject: CVE-2023-52752: smb: client: fix use-after-free bug in cifs_debug_data_proc_show()

From: Greg Kroah-Hartman <[email-masked]>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

smb: client: fix use-after-free bug in cifs_debug_data_proc_show()

Skip SMB sessions that are being teared down
(e.g. @ses->ses_status == SES_EXITING) in cifs_debug_data_proc_show()
to avoid use-after-free in @ses.

This fixes the following GPF when reading from /proc/fs/cifs/DebugData
while mounting and umounting

  [ 816.251274] general protection fault, probably for non-canonical
  address 0x6b6b6b6b6b6b6d81: 0000 [#1] PREEMPT SMP NOPTI
  ...
  [  816.260138] Call Trace:
  [  816.260329]  <TASK>
  [  816.260499]  ? die_addr+0x36/0x90
  [  816.260762]  ? exc_general_protection+0x1b3/0x410
  [  816.261126]  ? asm_exc_general_protection+0x26/0x30
  [  816.261502]  ? cifs_debug_tcon+0xbd/0x240 [cifs]
  [  816.261878]  ? cifs_debug_tcon+0xab/0x240 [cifs]
  [  816.262249]  cifs_debug_data_proc_show+0x516/0xdb0 [cifs]
  [  816.262689]  ? seq_read_iter+0x379/0x470
  [  816.262995]  seq_read_iter+0x118/0x470
  [  816.263291]  proc_reg_read_iter+0x53/0x90
  [  816.263596]  ? srso_alias_return_thunk+0x5/0x7f
  [  816.263945]  vfs_read+0x201/0x350
  [  816.264211]  ksys_read+0x75/0x100
  [  816.264472]  do_syscall_64+0x3f/0x90
  [  816.264750]  entry_SYSCALL_64_after_hwframe+0x6e/0xd8
  [  816.265135] RIP: 0033:0x7fd5e669d381

The Linux kernel CVE team has assigned CVE-2023-52752 to this issue.

Affected and fixed versions
===========================

	Fixed in 6.1.64 with commit 558817597d5f
	Fixed in 6.5.13 with commit 89929ea46f9c
	Fixed in 6.6.3 with commit 0ab6f842452c
	Fixed in 6.7 with commit d328c09ee9f1

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2023-52752
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	fs/smb/client/cifs_debug.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/558817597d5fbd7af31f891b67b0fd20f0d047b7
	https://git.kernel.org/stable/c/89929ea46f9cc11ba66d2c64713aa5d5dc723b09
	https://git.kernel.org/stable/c/0ab6f842452ce2cae04209d4671ac6289d0aef8a
	https://git.kernel.org/stable/c/d328c09ee9f15ee5a26431f5aad7c9239fa85e62