CVE-2026-72257: ASoC: qcom: q6apm: fix NULL pointer dereference in graph_callback

CVE-2026-72257: ASoC: qcom: q6apm: fix NULL pointer dereference in graph_callback

[Greg Kroah-Hartman]

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

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

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

ASoC: qcom: q6apm: fix NULL pointer dereference in graph_callback

When q6apm_free_fragments() is called it frees rx_data.buf/tx_data.buf
and sets them to NULL under graph->lock. A late DSP buffer-done response
can race with this: graph_callback() passes the !graph->ar_graph guard
(not yet NULL), acquires the lock, but then dereferences a now-NULL buf
pointer to read buf[token].phys, crashing at virtual address 0x10.

Add a NULL check for buf inside the mutex-protected section in both the
write-done (DATA_CMD_RSP_WR_SH_MEM_EP_DATA_BUFFER_DONE_V2) and
read-done (DATA_CMD_RSP_RD_SH_MEM_EP_DATA_BUFFER_V2) handlers and bail
out cleanly if buffers have already been freed.

This problem is only shown up recently while apr bus was updated to
process the commands per service rather from single global queue.

The Linux kernel CVE team has assigned CVE-2026-72257 to this issue.


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

	Issue introduced in 5.16 with commit 5477518b8a0e8a45239646acd80c9bafc4401522 and fixed in 6.1.178 with commit a164e744d8de1c41049bd9a1452a4b6bbf5bd8bc
	Issue introduced in 5.16 with commit 5477518b8a0e8a45239646acd80c9bafc4401522 and fixed in 6.6.145 with commit ec369eac0795cfa8f4d3a0cd35a1e8e15f780331
	Issue introduced in 5.16 with commit 5477518b8a0e8a45239646acd80c9bafc4401522 and fixed in 6.12.97 with commit 2c715f8a1e644ce4c3e8be5b0fd3f1f4704b73b3
	Issue introduced in 5.16 with commit 5477518b8a0e8a45239646acd80c9bafc4401522 and fixed in 6.18.40 with commit ca028334343a140efda4b22e53cbce2c5e94a489
	Issue introduced in 5.16 with commit 5477518b8a0e8a45239646acd80c9bafc4401522 and fixed in 7.1.5 with commit 214af790e3a33ab73587de4c925c60a550eae9c6
	Issue introduced in 5.16 with commit 5477518b8a0e8a45239646acd80c9bafc4401522 and fixed in 7.2-rc1 with commit 2e9261761b35f0b67b7487688cd1365f535be0b3

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-2026-72257
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:
	sound/soc/qcom/qdsp6/q6apm.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/a164e744d8de1c41049bd9a1452a4b6bbf5bd8bc
	https://git.kernel.org/stable/c/ec369eac0795cfa8f4d3a0cd35a1e8e15f780331
	https://git.kernel.org/stable/c/2c715f8a1e644ce4c3e8be5b0fd3f1f4704b73b3
	https://git.kernel.org/stable/c/ca028334343a140efda4b22e53cbce2c5e94a489
	https://git.kernel.org/stable/c/214af790e3a33ab73587de4c925c60a550eae9c6
	https://git.kernel.org/stable/c/2e9261761b35f0b67b7487688cd1365f535be0b3