Subject: CVE-2022-48918: iwlwifi: mvm: check debugfs_dir ptr before use

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

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

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

iwlwifi: mvm: check debugfs_dir ptr before use

When "debugfs=off" is used on the kernel command line, iwiwifi's
mvm module uses an invalid/unchecked debugfs_dir pointer and causes
a BUG:

 BUG: kernel NULL pointer dereference, address: 000000000000004f
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
 PGD 0 P4D 0
 Oops: 0000 [#1] PREEMPT SMP
 CPU: 1 PID: 503 Comm: modprobe Tainted: G        W         5.17.0-rc5 #7
 Hardware name: Dell Inc. Inspiron 15 5510/076F7Y, BIOS 2.4.1 11/05/2021
 RIP: 0010:iwl_mvm_dbgfs_register+0x692/0x700 [iwlmvm]
 Code: 69 a0 be 80 01 00 00 48 c7 c7 50 73 6a a0 e8 95 cf ee e0 48 8b 83 b0 1e 00 00 48 c7 c2 54 73 6a a0 be 64 00 00 00 48 8d 7d 8c <48> 8b 48 50 e8 15 22 07 e1 48 8b 43 28 48 8d 55 8c 48 c7 c7 5f 73
 RSP: 0018:ffffc90000a0ba68 EFLAGS: 00010246
 RAX: ffffffffffffffff RBX: ffff88817d6e3328 RCX: ffff88817d6e3328
 RDX: ffffffffa06a7354 RSI: 0000000000000064 RDI: ffffc90000a0ba6c
 RBP: ffffc90000a0bae0 R08: ffffffff824e4880 R09: ffffffffa069d620
 R10: ffffc90000a0ba00 R11: ffffffffffffffff R12: 0000000000000000
 R13: ffffc90000a0bb28 R14: ffff88817d6e3328 R15: ffff88817d6e3320
 FS:  00007f64dd92d740(0000) GS:ffff88847f640000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 000000000000004f CR3: 000000016fc79001 CR4: 0000000000770ee0
 PKRU: 55555554
 Call Trace:
  <TASK>
  ? iwl_mvm_mac_setup_register+0xbdc/0xda0 [iwlmvm]
  iwl_mvm_start_post_nvm+0x71/0x100 [iwlmvm]
  iwl_op_mode_mvm_start+0xab8/0xb30 [iwlmvm]
  _iwl_op_mode_start+0x6f/0xd0 [iwlwifi]
  iwl_opmode_register+0x6a/0xe0 [iwlwifi]
  ? 0xffffffffa0231000
  iwl_mvm_init+0x35/0x1000 [iwlmvm]
  ? 0xffffffffa0231000
  do_one_initcall+0x5a/0x1b0
  ? kmem_cache_alloc+0x1e5/0x2f0
  ? do_init_module+0x1e/0x220
  do_init_module+0x48/0x220
  load_module+0x2602/0x2bc0
  ? __kernel_read+0x145/0x2e0
  ? kernel_read_file+0x229/0x290
  __do_sys_finit_module+0xc5/0x130
  ? __do_sys_finit_module+0xc5/0x130
  __x64_sys_finit_module+0x13/0x20
  do_syscall_64+0x38/0x90
  entry_SYSCALL_64_after_hwframe+0x44/0xae
 RIP: 0033:0x7f64dda564dd
 Code: 5b 41 5c c3 66 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 1b 29 0f 00 f7 d8 64 89 01 48
 RSP: 002b:00007ffdba393f88 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f64dda564dd
 RDX: 0000000000000000 RSI: 00005575399e2ab2 RDI: 0000000000000001
 RBP: 000055753a91c5e0 R08: 0000000000000000 R09: 0000000000000002
 R10: 0000000000000001 R11: 0000000000000246 R12: 00005575399e2ab2
 R13: 000055753a91ceb0 R14: 0000000000000000 R15: 000055753a923018
  </TASK>
 Modules linked in: btintel(+) btmtk bluetooth vfat snd_hda_codec_hdmi fat snd_hda_codec_realtek snd_hda_codec_generic iwlmvm(+) snd_sof_pci_intel_tgl mac80211 snd_sof_intel_hda_common soundwire_intel soundwire_generic_allocation soundwire_cadence soundwire_bus snd_sof_intel_hda snd_sof_pci snd_sof snd_sof_xtensa_dsp snd_soc_hdac_hda snd_hda_ext_core snd_soc_acpi_intel_match snd_soc_acpi snd_soc_core btrfs snd_compress snd_hda_intel snd_intel_dspcfg snd_intel_sdw_acpi snd_hda_codec raid6_pq iwlwifi snd_hda_core snd_pcm snd_timer snd soundcore cfg80211 intel_ish_ipc(+) thunderbolt rfkill intel_ishtp ucsi_acpi wmi i2c_hid_acpi i2c_hid evdev
 CR2: 000000000000004f
 ---[ end trace 0000000000000000 ]---

Check the debugfs_dir pointer for an error before using it.

[change to make both conditional]

The Linux kernel CVE team has assigned CVE-2022-48918 to this issue.

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

	Issue introduced in 5.12 with commit 8c082a99edb9 and fixed in 5.15.27 with commit 7de1ed755e1a
	Issue introduced in 5.12 with commit 8c082a99edb9 and fixed in 5.16.13 with commit fe51975ff138
	Issue introduced in 5.12 with commit 8c082a99edb9 and fixed in 5.17 with commit 5a6248c0a223

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-2022-48918
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/net/wireless/intel/iwlwifi/mvm/debugfs.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/7de1ed755e1ace30d97a724bad32452ed86b653b
	https://git.kernel.org/stable/c/fe51975ff13831e794e1bcd0039b305dcad3d7ba
	https://git.kernel.org/stable/c/5a6248c0a22352f09ea041665d3bd3e18f6f872c