In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: Do not skip unrelated mode changes in DSC validation
Starting with commit 17ce8a6907f7 ("drm/amd/display: Add dsc pre-validation in
atomic check"), amdgpu resets the CRTC state mode_changed flag to false when
recomputing the DSC configuration results in no timing change for a particular
stream.
However, this is incorrect in scenarios where a change in MST/DSC configuration
happens in the same KMS commit as another (unrelated) mode change. For example,
the integrated panel of a laptop may be configured differently (e.g., HDR
enabled/disabled) depending on whether external screens are attached. In this
case, plugging in external DP-MST screens may result in the mode_changed flag
being dropped incorrectly for the integrated panel if its DSC configuration
did not change during precomputation in pre_validate_dsc().
At this point, however, dm_update_crtc_state() has already created new streams
for CRTCs with DSC-independent mode changes. In turn,
amdgpu_dm_commit_streams() will never release the old stream, resulting in a
memory leak. amdgpu_dm_atomic_commit_tail() will never acquire a reference to
the new stream either, which manifests as a use-after-free when the stream gets
disabled later on:
BUG: KASAN: use-after-free in dc_stream_release+0x25/0x90 [amdgpu]
Write of size 4 at addr ffff88813d836524 by task kworker/9:9/29977
Workqueue: events drm_mode_rmfb_work_fn
Call Trace:
<TASK>
dump_stack_lvl+0x6e/0xa0
print_address_description.constprop.0+0x88/0x320
? dc_stream_release+0x25/0x90 [amdgpu]
print_report+0xfc/0x1ff
? srso_alias_return_thunk+0x5/0xfbef5
? __virt_addr_valid+0x225/0x4e0
? dc_stream_release+0x25/0x90 [amdgpu]
kasan_report+0xe1/0x180
? dc_stream_release+0x25/0x90 [amdgpu]
kasan_check_range+0x125/0x200
dc_stream_release+0x25/0x90 [amdgpu]
dc_state_destruct+0x14d/0x5c0 [amdgpu]
dc_state_release.part.0+0x4e/0x130 [amdgpu]
dm_atomic_destroy_state+0x3f/0x70 [amdgpu]
drm_atomic_state_default_clear+0x8ee/0xf30
? drm_mode_object_put.part.0+0xb1/0x130
__drm_atomic_state_free+0x15c/0x2d0
atomic_remove_fb+0x67e/0x980
Since there is no reliable way of figuring out whether a CRTC has unrelated
mode changes pending at the time of DSC validation, remember the value of the
mode_changed flag from before the point where a CRTC was marked as potentially
affected by a change in DSC configuration. Reset the mode_changed flag to this
earlier value instead in pre_validate_dsc().
(cherry picked from commit cc7c7121ae082b7b82891baa7280f1ff2608f22b)
drm/amd/display: Do not skip unrelated mode changes in DSC validation
Starting with commit 17ce8a6907f7 ("drm/amd/display: Add dsc pre-validation in
atomic check"), amdgpu resets the CRTC state mode_changed flag to false when
recomputing the DSC configuration results in no timing change for a particular
stream.
However, this is incorrect in scenarios where a change in MST/DSC configuration
happens in the same KMS commit as another (unrelated) mode change. For example,
the integrated panel of a laptop may be configured differently (e.g., HDR
enabled/disabled) depending on whether external screens are attached. In this
case, plugging in external DP-MST screens may result in the mode_changed flag
being dropped incorrectly for the integrated panel if its DSC configuration
did not change during precomputation in pre_validate_dsc().
At this point, however, dm_update_crtc_state() has already created new streams
for CRTCs with DSC-independent mode changes. In turn,
amdgpu_dm_commit_streams() will never release the old stream, resulting in a
memory leak. amdgpu_dm_atomic_commit_tail() will never acquire a reference to
the new stream either, which manifests as a use-after-free when the stream gets
disabled later on:
BUG: KASAN: use-after-free in dc_stream_release+0x25/0x90 [amdgpu]
Write of size 4 at addr ffff88813d836524 by task kworker/9:9/29977
Workqueue: events drm_mode_rmfb_work_fn
Call Trace:
<TASK>
dump_stack_lvl+0x6e/0xa0
print_address_description.constprop.0+0x88/0x320
? dc_stream_release+0x25/0x90 [amdgpu]
print_report+0xfc/0x1ff
? srso_alias_return_thunk+0x5/0xfbef5
? __virt_addr_valid+0x225/0x4e0
? dc_stream_release+0x25/0x90 [amdgpu]
kasan_report+0xe1/0x180
? dc_stream_release+0x25/0x90 [amdgpu]
kasan_check_range+0x125/0x200
dc_stream_release+0x25/0x90 [amdgpu]
dc_state_destruct+0x14d/0x5c0 [amdgpu]
dc_state_release.part.0+0x4e/0x130 [amdgpu]
dm_atomic_destroy_state+0x3f/0x70 [amdgpu]
drm_atomic_state_default_clear+0x8ee/0xf30
? drm_mode_object_put.part.0+0xb1/0x130
__drm_atomic_state_free+0x15c/0x2d0
atomic_remove_fb+0x67e/0x980
Since there is no reliable way of figuring out whether a CRTC has unrelated
mode changes pending at the time of DSC validation, remember the value of the
mode_changed flag from before the point where a CRTC was marked as potentially
affected by a change in DSC configuration. Reset the mode_changed flag to this
earlier value instead in pre_validate_dsc().
(cherry picked from commit cc7c7121ae082b7b82891baa7280f1ff2608f22b)
Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Thu, 23 Apr 2026 00:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
|
Wed, 22 Apr 2026 14:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: Do not skip unrelated mode changes in DSC validation Starting with commit 17ce8a6907f7 ("drm/amd/display: Add dsc pre-validation in atomic check"), amdgpu resets the CRTC state mode_changed flag to false when recomputing the DSC configuration results in no timing change for a particular stream. However, this is incorrect in scenarios where a change in MST/DSC configuration happens in the same KMS commit as another (unrelated) mode change. For example, the integrated panel of a laptop may be configured differently (e.g., HDR enabled/disabled) depending on whether external screens are attached. In this case, plugging in external DP-MST screens may result in the mode_changed flag being dropped incorrectly for the integrated panel if its DSC configuration did not change during precomputation in pre_validate_dsc(). At this point, however, dm_update_crtc_state() has already created new streams for CRTCs with DSC-independent mode changes. In turn, amdgpu_dm_commit_streams() will never release the old stream, resulting in a memory leak. amdgpu_dm_atomic_commit_tail() will never acquire a reference to the new stream either, which manifests as a use-after-free when the stream gets disabled later on: BUG: KASAN: use-after-free in dc_stream_release+0x25/0x90 [amdgpu] Write of size 4 at addr ffff88813d836524 by task kworker/9:9/29977 Workqueue: events drm_mode_rmfb_work_fn Call Trace: <TASK> dump_stack_lvl+0x6e/0xa0 print_address_description.constprop.0+0x88/0x320 ? dc_stream_release+0x25/0x90 [amdgpu] print_report+0xfc/0x1ff ? srso_alias_return_thunk+0x5/0xfbef5 ? __virt_addr_valid+0x225/0x4e0 ? dc_stream_release+0x25/0x90 [amdgpu] kasan_report+0xe1/0x180 ? dc_stream_release+0x25/0x90 [amdgpu] kasan_check_range+0x125/0x200 dc_stream_release+0x25/0x90 [amdgpu] dc_state_destruct+0x14d/0x5c0 [amdgpu] dc_state_release.part.0+0x4e/0x130 [amdgpu] dm_atomic_destroy_state+0x3f/0x70 [amdgpu] drm_atomic_state_default_clear+0x8ee/0xf30 ? drm_mode_object_put.part.0+0xb1/0x130 __drm_atomic_state_free+0x15c/0x2d0 atomic_remove_fb+0x67e/0x980 Since there is no reliable way of figuring out whether a CRTC has unrelated mode changes pending at the time of DSC validation, remember the value of the mode_changed flag from before the point where a CRTC was marked as potentially affected by a change in DSC configuration. Reset the mode_changed flag to this earlier value instead in pre_validate_dsc(). (cherry picked from commit cc7c7121ae082b7b82891baa7280f1ff2608f22b) | |
| Title | drm/amd/display: Do not skip unrelated mode changes in DSC validation | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Projects
Sign in to view the affected projects.
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-04-22T13:54:12.963Z
Reserved: 2026-03-09T15:48:24.101Z
Link: CVE-2026-31488
No data.
Status : Received
Published: 2026-04-22T14:16:46.453
Modified: 2026-04-22T14:16:46.453
Link: CVE-2026-31488
OpenCVE Enrichment
Updated: 2026-04-22T18:30:23Z
Weaknesses
No weakness.