CVE-2026-68103: drm/amdgpu: reject mapping a reserved doorbell to a new queue

CVE-2026-68103: drm/amdgpu: reject mapping a reserved doorbell to a new queue

[Greg Kroah-Hartman]

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

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

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

drm/amdgpu: reject mapping a reserved doorbell to a new queue

When creating an user-queue, the user space
provides a doorbell BO handle and an offset within
the bo to obtain a doorbell.

However current implementation using xa_store_irq()
to store a doorbell, which allows a later queue created
with the same BO and offset parameters to overwrite an
existing queue and doorbell mapping.

This can cause problems like misrouting fence IRQ
processing to a wrong queue, and mislead the cleanup
process of one queue erasing the mapping of another queue.

This commit fixes this issue by replacing xa_store_irq with
xa_insert_irq, which rejects mapping a reserved
doorbell to a newly created queue

(cherry picked from commit 6244eae22966350db52faf9c1369d3b2ffc5de4e)

The Linux kernel CVE team has assigned CVE-2026-68103 to this issue.


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

	Fixed in 7.1.6 with commit 1050d258c7c56066d2dcaedf8d0ef66364062adc
	Fixed in 7.2-rc2 with commit a609b6278bf3cde17eeee6620091465521e4b02c

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-2026-68103
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/amdgpu/amdgpu_userq.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/1050d258c7c56066d2dcaedf8d0ef66364062adc
	https://git.kernel.org/stable/c/a609b6278bf3cde17eeee6620091465521e4b02c