Subject: CVE-2024-27042: drm/amdgpu: Fix potential out-of-bounds access in 'amdgpu_discovery_reg_base_init()'

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

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

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

drm/amdgpu: Fix potential out-of-bounds access in 'amdgpu_discovery_reg_base_init()'

The issue arises when the array 'adev->vcn.vcn_config' is accessed
before checking if the index 'adev->vcn.num_vcn_inst' is within the
bounds of the array.

The fix involves moving the bounds check before the array access. This
ensures that 'adev->vcn.num_vcn_inst' is within the bounds of the array
before it is used as an index.

Fixes the below:
drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c:1289 amdgpu_discovery_reg_base_init() error: testing array offset 'adev->vcn.num_vcn_inst' after use.

The Linux kernel CVE team has assigned CVE-2024-27042 to this issue.

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

	Issue introduced in 5.19 with commit a0ccc717c4ab and fixed in 6.6.23 with commit 8f3e68c6a3ff
	Issue introduced in 5.19 with commit a0ccc717c4ab and fixed in 6.7.11 with commit b33d4af102b9
	Issue introduced in 5.19 with commit a0ccc717c4ab and fixed in 6.8.2 with commit 8db10cee51e3
	Issue introduced in 5.19 with commit a0ccc717c4ab and fixed in 6.9 with commit cdb637d33957

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-2024-27042
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_discovery.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/8f3e68c6a3fff53c2240762a47a0045d89371775
	https://git.kernel.org/stable/c/b33d4af102b9c1f7a83d3f0ad3cab7d2bab8f058
	https://git.kernel.org/stable/c/8db10cee51e3e11a6658742465edc21986cf1e8d
	https://git.kernel.org/stable/c/cdb637d339572398821204a1142d8d615668f1e9