CVE-2026-68380: accel/amdxdna: Fix use-after-free of mm_struct in job scheduler

Greg Kroah-Hartman <[email protected]>
Newsgroups org.kernel.vger.linux-cve-announce
Message-ID <2026081044-CVE-2026-68380-abce@gregkh>
From: Greg Kroah-Hartman <[email protected]>

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

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

accel/amdxdna: Fix use-after-free of mm_struct in job scheduler

amdxdna_cmd_submit() stores current->mm in job->mm without holding any
reference. aie2_sched_job_run() later access job->mm from the DRM
scheduler worker thread. With only a raw pointer and no structural
reference, the mm_struct can be freed before the scheduler runs the job.

Fix this by calling mmgrab() to hold a structural mm_count reference for
the lifetime of the job, paired with mmdrop() in every cleanup path.

The Linux kernel CVE team has assigned CVE-2026-68380 to this issue.


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

	Issue introduced in 6.14 with commit aac243092b707bb3018e951d470cc1a9bcbaba6c and fixed in 6.18.42 with commit 6875ee2bef48f5d9f045d81a8a4d68893f768a8a
	Issue introduced in 6.14 with commit aac243092b707bb3018e951d470cc1a9bcbaba6c and fixed in 7.1.6 with commit e8fadbffc19a233d1eedebfb8df0f522d1388280
	Issue introduced in 6.14 with commit aac243092b707bb3018e951d470cc1a9bcbaba6c and fixed in 7.2-rc4 with commit faebb7ba1ac65fa5810b640df02ce04e509fdc11

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-2026-68380
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/accel/amdxdna/amdxdna_ctx.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/6875ee2bef48f5d9f045d81a8a4d68893f768a8a
	https://git.kernel.org/stable/c/e8fadbffc19a233d1eedebfb8df0f522d1388280
	https://git.kernel.org/stable/c/faebb7ba1ac65fa5810b640df02ce04e509fdc11
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