Subject: CVE-2021-47027: mt76: mt7921: fix kernel crash when the firmware fails to download

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

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

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

mt76: mt7921: fix kernel crash when the firmware fails to download

Fix kernel crash when the firmware is missing or fails to download.

[    9.444758] kernel BUG at drivers/pci/msi.c:375!
[    9.449363] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
[    9.501033] pstate: a0400009 (NzCv daif +PAN -UAO)
[    9.505814] pc : free_msi_irqs+0x180/0x184
[    9.509897] lr : free_msi_irqs+0x40/0x184
[    9.513893] sp : ffffffc015193870
[    9.517194] x29: ffffffc015193870 x28: 00000000f0e94fa2
[    9.522492] x27: 0000000000000acd x26: 000000000000009a
[    9.527790] x25: ffffffc0152cee58 x24: ffffffdbb383e0d8
[    9.533087] x23: ffffffdbb38628d0 x22: 0000000000040200
[    9.538384] x21: ffffff8cf7de7318 x20: ffffff8cd65a2480
[    9.543681] x19: ffffff8cf7de7000 x18: 0000000000000000
[    9.548979] x17: ffffff8cf9ca03b4 x16: ffffffdc13ad9a34
[    9.554277] x15: 0000000000000000 x14: 0000000000080800
[    9.559575] x13: ffffff8cd65a2980 x12: 0000000000000000
[    9.564873] x11: ffffff8cfa45d820 x10: ffffff8cfa45d6d0
[    9.570171] x9 : 0000000000000040 x8 : ffffff8ccef1b780
[    9.575469] x7 : aaaaaaaaaaaaaaaa x6 : 0000000000000000
[    9.580766] x5 : ffffffdc13824900 x4 : ffffff8ccefe0000
[    9.586063] x3 : 0000000000000000 x2 : 0000000000000000
[    9.591362] x1 : 0000000000000125 x0 : ffffff8ccefe0000
[    9.596660] Call trace:
[    9.599095]  free_msi_irqs+0x180/0x184
[    9.602831]  pci_disable_msi+0x100/0x130
[    9.606740]  pci_free_irq_vectors+0x24/0x30
[    9.610915]  mt7921_pci_probe+0xbc/0x250 [mt7921e]
[    9.615693]  pci_device_probe+0xd4/0x14c
[    9.619604]  really_probe+0x134/0x2ec
[    9.623252]  driver_probe_device+0x64/0xfc
[    9.627335]  device_driver_attach+0x4c/0x6c
[    9.631506]  __driver_attach+0xac/0xc0
[    9.635243]  bus_for_each_dev+0x8c/0xd4
[    9.639066]  driver_attach+0x2c/0x38
[    9.642628]  bus_add_driver+0xfc/0x1d0
[    9.646365]  driver_register+0x64/0xf8
[    9.650101]  __pci_register_driver+0x6c/0x7c
[    9.654360]  init_module+0x28/0xfdc [mt7921e]
[    9.658704]  do_one_initcall+0x13c/0x2d0
[    9.662615]  do_init_module+0x58/0x1e8
[    9.666351]  load_module+0xd80/0xeb4
[    9.669912]  __arm64_sys_finit_module+0xa8/0xe0
[    9.674430]  el0_svc_common+0xa4/0x16c
[    9.678168]  el0_svc_compat_handler+0x2c/0x40
[    9.682511]  el0_svc_compat+0x8/0x10
[    9.686076] Code: a94257f6 f9400bf7 a8c47bfd d65f03c0 (d4210000)
[    9.692155] ---[ end trace 7621f966afbf0a29 ]---
[    9.697385] Kernel panic - not syncing: Fatal exception
[    9.702599] SMP: stopping secondary CPUs
[    9.706549] Kernel Offset: 0x1c03600000 from 0xffffffc010000000
[    9.712456] PHYS_OFFSET: 0xfffffff440000000
[    9.716625] CPU features: 0x080026,2a80aa18
[    9.720795] Memory Limit: none

The Linux kernel CVE team has assigned CVE-2021-47027 to this issue.

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

	Issue introduced in 5.12 with commit 5c14a5f944b9 and fixed in 5.12.4 with commit a46b536cd60c
	Issue introduced in 5.12 with commit 5c14a5f944b9 and fixed in 5.13 with commit e230f0c44f01

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-2021-47027
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/mediatek/mt76/mt7921/pci.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/a46b536cd60c0dbd4bf767c62a8774dec52bf099
	https://git.kernel.org/stable/c/e230f0c44f011f3270680a506b19b7e84c5e8923