Executive brief
The Linux kernel's AMD graphics display driver has a bug in the display turn-off function for HDMI connections on older AMD GPUs (Southern Islands). When disabling display output, the code attempts to call a function without checking if it exists, causing the system to crash. This primarily affects users with older AMD discrete graphics cards when powering off HDMI displays.
Technical details
The vulnerability is a NULL pointer dereference in the dce110_set_avmute function within the AMD display driver's hardware sequencer component. The function unconditionally calls is_tg_enabled on the timing generator without first verifying that the timing generator object exists or that the required function pointers are populated in its operations table. On older DCE (Display Core Engine) timing generators used in Southern Islands dGPUs, the is_tg_enabled and wait_for_state function pointers are not implemented, causing a crash when turning off HDMI display output. The fix adds explicit NULL checks for the timing generator object and its required function pointers before attempting to call them. This is a local denial-of-service issue triggered through normal display disable operations.
Affected products
- Linux Linux kernel various versions with AMD display driver prior to fix commit 2686a0c0aaa07bec2e24131835cf27b5fd4935a5
Timeline
- 2026-08-22: disclosed
- 2026-08-05: patched: Original patch commit 2686a0c0aaa07bec2e24131835cf27b5fd4935a5
- 2026-08-06: other: Cherry-picked to stable kernel by Alex Deucher