Subject: CVE-2023-52808: scsi: hisi_sas: Set debugfs_dir pointer to NULL after removing debugfs

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

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

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

scsi: hisi_sas: Set debugfs_dir pointer to NULL after removing debugfs

If init debugfs failed during device registration due to memory allocation
failure, debugfs_remove_recursive() is called, after which debugfs_dir is
not set to NULL. debugfs_remove_recursive() will be called again during
device removal. As a result, illegal pointer is accessed.

[ 1665.467244] hisi_sas_v3_hw 0000:b4:02.0: failed to init debugfs!
...
[ 1669.836708] Unable to handle kernel NULL pointer dereference at virtual address 00000000000000a0
[ 1669.872669] pc : down_write+0x24/0x70
[ 1669.876315] lr : down_write+0x1c/0x70
[ 1669.879961] sp : ffff000036f53a30
[ 1669.883260] x29: ffff000036f53a30 x28: ffffa027c31549f8
[ 1669.888547] x27: ffffa027c3140000 x26: 0000000000000000
[ 1669.893834] x25: ffffa027bf37c270 x24: ffffa027bf37c270
[ 1669.899122] x23: ffff0000095406b8 x22: ffff0000095406a8
[ 1669.904408] x21: 0000000000000000 x20: ffffa027bf37c310
[ 1669.909695] x19: 00000000000000a0 x18: ffff8027dcd86f10
[ 1669.914982] x17: 0000000000000000 x16: 0000000000000000
[ 1669.920268] x15: 0000000000000000 x14: ffffa0274014f870
[ 1669.925555] x13: 0000000000000040 x12: 0000000000000228
[ 1669.930842] x11: 0000000000000020 x10: 0000000000000bb0
[ 1669.936129] x9 : ffff000036f537f0 x8 : ffff80273088ca10
[ 1669.941416] x7 : 000000000000001d x6 : 00000000ffffffff
[ 1669.946702] x5 : ffff000008a36310 x4 : ffff80273088be00
[ 1669.951989] x3 : ffff000009513e90 x2 : 0000000000000000
[ 1669.957276] x1 : 00000000000000a0 x0 : ffffffff00000001
[ 1669.962563] Call trace:
[ 1669.965000]  down_write+0x24/0x70
[ 1669.968301]  debugfs_remove_recursive+0x5c/0x1b0
[ 1669.972905]  hisi_sas_debugfs_exit+0x24/0x30 [hisi_sas_main]
[ 1669.978541]  hisi_sas_v3_remove+0x130/0x150 [hisi_sas_v3_hw]
[ 1669.984175]  pci_device_remove+0x48/0xd8
[ 1669.988082]  device_release_driver_internal+0x1b4/0x250
[ 1669.993282]  device_release_driver+0x28/0x38
[ 1669.997534]  pci_stop_bus_device+0x84/0xb8
[ 1670.001611]  pci_stop_and_remove_bus_device_locked+0x24/0x40
[ 1670.007244]  remove_store+0xfc/0x140
[ 1670.010802]  dev_attr_store+0x44/0x60
[ 1670.014448]  sysfs_kf_write+0x58/0x80
[ 1670.018095]  kernfs_fop_write+0xe8/0x1f0
[ 1670.022000]  __vfs_write+0x60/0x190
[ 1670.025472]  vfs_write+0xac/0x1c0
[ 1670.028771]  ksys_write+0x6c/0xd8
[ 1670.032071]  __arm64_sys_write+0x24/0x30
[ 1670.035977]  el0_svc_common+0x78/0x130
[ 1670.039710]  el0_svc_handler+0x38/0x78
[ 1670.043442]  el0_svc+0x8/0xc

To fix this, set debugfs_dir to NULL after debugfs_remove_recursive().

The Linux kernel CVE team has assigned CVE-2023-52808 to this issue.

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

	Fixed in 5.15.140 with commit f0bfc8a5561f
	Fixed in 6.1.64 with commit 33331b265aac
	Fixed in 6.5.13 with commit 75a2656260fe
	Fixed in 6.6.3 with commit b4465009e7d6
	Fixed in 6.7 with commit 6de426f9276c

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-2023-52808
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:
	drivers/scsi/hisi_sas/hisi_sas_v3_hw.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/f0bfc8a5561fb0b2c48183dcbfe00bdd6d973bd3
	https://git.kernel.org/stable/c/33331b265aac9441ac0c1a5442e3f05d038240ec
	https://git.kernel.org/stable/c/75a2656260fe8c7eeabda6ff4600b29e183f48db
	https://git.kernel.org/stable/c/b4465009e7d60c6111946db4c8f1e50d401ed7be
	https://git.kernel.org/stable/c/6de426f9276c448e2db7238911c97fb157cb23be