Linux Kernel AMDGPU VCN User Fence Vulnerability in Encoder/Decoder Rings

A vulnerability in the Linux kernel's AMDGPU VCN 4.0.5 encoder and decoder rings has been addressed. These rings do not support 64-bit user fence writes, leading to a rejection of command submissions that include user fences. The issue has been fixed by setting the 'no_user_fence' option for the VCN 4.0.5 encoding ring.

Impact

The vulnerability could lead to improper handling of command submissions with user fences, potentially causing issues in graphics processing or video encoding/decoding tasks that rely on the VCN hardware acceleration.

Reproduction

The vulnerability can be reproduced by attempting to submit command streams (CS) to the VCN 4.0.5 encoder or decoder rings with 64-bit user fences. The submission will be rejected, indicating that the rings do not support this type of user fence write.

Remediation

Users can update to the latest version of the Linux kernel where this vulnerability has been fixed. Instructions for downloading the patched kernel can be found on the official Linux kernel website.