Executive brief
A vulnerability was identified in the Linux kernel's AMD GPU driver where certain video encoding and decoding components (VCN v4.0) incorrectly handled memory synchronization requests. This could lead to system instability or unexpected behavior when processing video data. The issue has been resolved by ensuring the system rejects unsupported synchronization requests that the hardware cannot safely process.
Technical details
A vulnerability in the Linux kernel's 'amdgpu' driver (specifically within 'vcn_v4_0.c') stems from the VCN v4.0 encoder and decoder rings not supporting 64-bit user fence writes. Without the 'no_user_fence' flag set, the driver might attempt to process Command Stream (CS) submissions containing these unsupported fences. An attacker with local access to the GPU interface could potentially trigger undefined behavior or kernel instability by submitting malformed CS requests. The fix involves setting the '.no_user_fence = true' flag in the 'amdgpu_ring_funcs' structure for VCN v4.0 to explicitly reject such submissions.
Affected products
- Linux Linux 5.19 to 7.1
Timeline
- 2026-07-19: disclosed
- 2026-07-19: advisory