CVE-2026-68275: drm/amdgpu: check amdgpu_vm_bo_find() result in GET_MAPPING_INFO

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

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

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

drm/amdgpu: check amdgpu_vm_bo_find() result in GET_MAPPING_INFO

The AMDGPU_GEM_OP_GET_MAPPING_INFO path of amdgpu_gem_op_ioctl() looks
up the bo_va for the buffer object in the caller's VM via
amdgpu_vm_bo_find(), but uses the returned pointer without checking it.

amdgpu_vm_bo_find() returns NULL when the BO has no bo_va in that VM,
which is the normal case for a BO that has never been mapped. The result
is fed straight into amdgpu_vm_bo_va_for_each_valid_mapping(), which
expands to list_for_each_entry(mapping, &(bo_va)->valids, list) and
dereferences bo_va, causing a NULL pointer dereference.

This is reachable by any process able to issue the ioctl (render group)
simply by requesting mapping info for an unmapped BO.

Return -ENOENT when no bo_va is found, jumping to out_exec so the
drm_exec context and GEM object reference are released.

(cherry picked from commit 528b19377affc1cc7362a70a254c1dda793595f9)

The Linux kernel CVE team has assigned CVE-2026-68275 to this issue.


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

	Issue introduced in 6.18 with commit 4d82724f7f2b847eb0454b1aab5450545b39abd4 and fixed in 6.18.42 with commit ddba17b3dfa0efc80d6c98621c2fb7af66adb622
	Issue introduced in 6.18 with commit 4d82724f7f2b847eb0454b1aab5450545b39abd4 and fixed in 7.1.6 with commit 9faf4c66edb6bcb8ca0465c3a4868bb7f278cd31
	Issue introduced in 6.18 with commit 4d82724f7f2b847eb0454b1aab5450545b39abd4 and fixed in 7.2-rc1 with commit 93475c34111916df71c63e510fc52db01351f809

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-2026-68275
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_gem.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/ddba17b3dfa0efc80d6c98621c2fb7af66adb622
	https://git.kernel.org/stable/c/9faf4c66edb6bcb8ca0465c3a4868bb7f278cd31
	https://git.kernel.org/stable/c/93475c34111916df71c63e510fc52db01351f809