linux-cve-announce - CVE-2021-4460: drm/amdkfd: Fix UBSAN shift-out-of-bounds warning

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Message-ID: <2025100114-CVE-2021-4460-aa71@gregkh>
Date: Wed,  1 Oct 2025 13:45:14 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2021-4460: drm/amdkfd: Fix UBSAN shift-out-of-bounds warning

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

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

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

drm/amdkfd: Fix UBSAN shift-out-of-bounds warning

If get_num_sdma_queues or get_num_xgmi_sdma_queues is 0, we end up
doing a shift operation where the number of bits shifted equals
number of bits in the operand. This behaviour is undefined.

Set num_sdma_queues or num_xgmi_sdma_queues to ULLONG_MAX, if the
count is >= number of bits in the operand.

Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1472

The Linux kernel CVE team has assigned CVE-2021-4460 to this issue.


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

	Fixed in 5.4.118 with commit 0c0356ef2498c1a250fe3846f30293f828737309
	Fixed in 5.10.36 with commit 1874b0ef1426b873de94c61861e38f29a8df714c
	Fixed in 5.11.20 with commit 3fdc5182700910a685d23df57d65166e8556a266
	Fixed in 5.12.3 with commit 9069b1b542de8f3bbffef868aff41521b21485cf
	Fixed in 5.13 with commit 50e2fc36e72d4ad672032ebf646cecb48656efe0

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-2021-4460
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/gpu/drm/amd/amdkfd/kfd_device_queue_manager.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/0c0356ef2498c1a250fe3846f30293f828737309
	https://git.kernel.org/stable/c/1874b0ef1426b873de94c61861e38f29a8df714c
	https://git.kernel.org/stable/c/3fdc5182700910a685d23df57d65166e8556a266
	https://git.kernel.org/stable/c/9069b1b542de8f3bbffef868aff41521b21485cf
	https://git.kernel.org/stable/c/50e2fc36e72d4ad672032ebf646cecb48656efe0