linux-cve-announce - CVE-2025-40034: PCI/AER: Avoid NULL pointer dereference in aer

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Message-ID: <2025102811-CVE-2025-40034-e836@gregkh>
Date: Tue, 28 Oct 2025 12:48:11 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-40034: PCI/AER: Avoid NULL pointer dereference in aer_ratelimit()

From: Greg Kroah-Hartman <gregkh@...nel.org>

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

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

PCI/AER: Avoid NULL pointer dereference in aer_ratelimit()

When platform firmware supplies error information to the OS, e.g., via the
ACPI APEI GHES mechanism, it may identify an error source device that
doesn't advertise an AER Capability and therefore dev->aer_info, which
contains AER stats and ratelimiting data, is NULL.

pci_dev_aer_stats_incr() already checks dev->aer_info for NULL, but
aer_ratelimit() did not, leading to NULL pointer dereferences like this one
from the URL below:

  {1}[Hardware Error]: Hardware error from APEI Generic Hardware Error Source: 0
  {1}[Hardware Error]: event severity: corrected
  {1}[Hardware Error]:   device_id: 0000:00:00.0
  {1}[Hardware Error]:   vendor_id: 0x8086, device_id: 0x2020
  {1}[Hardware Error]:   aer_cor_status: 0x00001000, aer_cor_mask: 0x00002000
  BUG: kernel NULL pointer dereference, address: 0000000000000264
  RIP: 0010:___ratelimit+0xc/0x1b0
  pci_print_aer+0x141/0x360
  aer_recover_work_func+0xb5/0x130

[8086:2020] is an Intel "Sky Lake-E DMI3 Registers" device that claims to
be a Root Port but does not advertise an AER Capability.

Add a NULL check in aer_ratelimit() to avoid the NULL pointer dereference.
Note that this also prevents ratelimiting these events from GHES.

[bhelgaas: add crash details to commit log]

The Linux kernel CVE team has assigned CVE-2025-40034 to this issue.


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

	Issue introduced in 6.16 with commit a57f2bfb4a5863f83087867c0e671f2418212d23 and fixed in 6.17.3 with commit 41683624cbff0a26bb7e0627f4a7e1b51a8779a8
	Issue introduced in 6.16 with commit a57f2bfb4a5863f83087867c0e671f2418212d23 and fixed in 6.18-rc1 with commit deb2f228388ff3a9d0623e3b59a053e9235c341d

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-2025-40034
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/pci/pcie/aer.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/41683624cbff0a26bb7e0627f4a7e1b51a8779a8
	https://git.kernel.org/stable/c/deb2f228388ff3a9d0623e3b59a053e9235c341d