CVE-2026-68257: drm/amdkfd: fix 32-bit overflow in CWSR total size calculation

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

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

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

drm/amdkfd: fix 32-bit overflow in CWSR total size calculation

total_cwsr_size was computed in 32-bit before being used as a BO/SVM
allocation size.
With large ctx_save_restore_area_size and debug_memory_size
multiplied by the XCC count, the product can wrap,
yielding an undersized CWSR save area that firmware later overruns.

Promote total_cwsr_size to u64 and use check_add_overflow()/
check_mul_overflow() in both kfd_queue_acquire_buffers() and
kfd_queue_release_buffers().

(cherry picked from commit 319f7e13423ae3f486b9aea82f9ad2d6af0ee608)

The Linux kernel CVE team has assigned CVE-2026-68257 to this issue.


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

	Fixed in 6.12.101 with commit b88ffe6593607364a8c06a48c6f29e55437cdf8e
	Fixed in 6.18.42 with commit abce3276c57e36c955627307469b9f009057a467
	Fixed in 7.1.6 with commit 865532d54eb57b660b1cb1b0e1755776ce21b849
	Fixed in 7.2-rc4 with commit 2b0386d4293920e690c0e017708f999b93cc729b

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-2026-68257
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_queue.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/b88ffe6593607364a8c06a48c6f29e55437cdf8e
	https://git.kernel.org/stable/c/abce3276c57e36c955627307469b9f009057a467
	https://git.kernel.org/stable/c/865532d54eb57b660b1cb1b0e1755776ce21b849
	https://git.kernel.org/stable/c/2b0386d4293920e690c0e017708f999b93cc729b