Executive brief
The Linux kernel's AMD graphics display driver failed to check whether phantom plane memory allocation succeeded before using the allocated memory, potentially causing a system crash. This affects systems with AMD graphics hardware running vulnerable kernel versions, leading to a denial of service when display mode changes occur.
Technical details
The vulnerability is a missing error check in the drm/amd/display subsystem's dml21_handle_phantom_streams_planes() function. The dml21_add_phantom_plane() function call was invoked without verifying its return status, which could indicate allocation failure. If memory allocation failed, the function would return without setting the phantom plane correctly, leading to a null pointer dereference (segmentation fault) on subsequent access to the uninitialized phantom plane data structure. The fix adds an if-statement to verify successful allocation before setting the phantoms_added flag. The vulnerability is local to systems with AMD graphics hardware and is triggered during display mode programming operations.
Affected products
- Linux Linux kernel various (introduced in commit 70839da63605, patched in stable branches)
Timeline
- 2026-08-28: disclosed
- 2026-02-16: patched: Upstream patch committed
- 2026-08-09: patched: Stable backport applied