CVE-2026-64234: tty: serial: pch_uart: add check for dma_alloc_coherent()

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

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

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

tty: serial: pch_uart: add check for dma_alloc_coherent()

Add a check for dma_alloc_coherent() failure to prevent a potential
NULL pointer dereference in dma_handle_rx(). Properly release DMA
channels and the PCI device reference using a goto ladder if the
allocation fails.

The Linux kernel CVE team has assigned CVE-2026-64234 to this issue.


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

	Issue introduced in 2.6.38 with commit 3c6a483275f47a2ef7119309ad3d791c10cf30da and fixed in 5.10.259 with commit 760df81763b391bb5f0dcb0b7597b736da753ae4
	Issue introduced in 2.6.38 with commit 3c6a483275f47a2ef7119309ad3d791c10cf30da and fixed in 5.15.210 with commit 5f2e2a240dc1846e049bc67e9c3cdf5b031d08bf
	Issue introduced in 2.6.38 with commit 3c6a483275f47a2ef7119309ad3d791c10cf30da and fixed in 6.1.176 with commit daea997bb244aeb50cbb2e5e075fb446a6cf068f
	Issue introduced in 2.6.38 with commit 3c6a483275f47a2ef7119309ad3d791c10cf30da and fixed in 6.6.143 with commit 6dd5c0ea139b586ad5a091677056dafd405cfe82
	Issue introduced in 2.6.38 with commit 3c6a483275f47a2ef7119309ad3d791c10cf30da and fixed in 6.12.93 with commit d846df2dfbc2469a688833b4cc4f8aa80672bde8
	Issue introduced in 2.6.38 with commit 3c6a483275f47a2ef7119309ad3d791c10cf30da and fixed in 6.18.35 with commit 66f8bfea055b23719b4fd6ce207c44de37d82a59
	Issue introduced in 2.6.38 with commit 3c6a483275f47a2ef7119309ad3d791c10cf30da and fixed in 7.0.12 with commit d8d53a343ebe74274ca17b1e1993042e99f8c863
	Issue introduced in 2.6.38 with commit 3c6a483275f47a2ef7119309ad3d791c10cf30da and fixed in 7.1 with commit 6fe472c1bbbe238e91141f7cabc1226e96a60d43

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-2026-64234
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/tty/serial/pch_uart.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/760df81763b391bb5f0dcb0b7597b736da753ae4
	https://git.kernel.org/stable/c/5f2e2a240dc1846e049bc67e9c3cdf5b031d08bf
	https://git.kernel.org/stable/c/daea997bb244aeb50cbb2e5e075fb446a6cf068f
	https://git.kernel.org/stable/c/6dd5c0ea139b586ad5a091677056dafd405cfe82
	https://git.kernel.org/stable/c/d846df2dfbc2469a688833b4cc4f8aa80672bde8
	https://git.kernel.org/stable/c/66f8bfea055b23719b4fd6ce207c44de37d82a59
	https://git.kernel.org/stable/c/d8d53a343ebe74274ca17b1e1993042e99f8c863
	https://git.kernel.org/stable/c/6fe472c1bbbe238e91141f7cabc1226e96a60d43