CVE-2026-53138

In the Linux kernel, the following vulnerability has been resolved:

drm/amd/display: Bound VBIOS record-chain walk loops

[Why & How] All record-chain walk loops in biosparser.c and biosparser2.c use for(;;) and only terminate on a 0xFF recordtype sentinel or zero recordsize. A malformed VBIOS image missing the terminator record causes unbounded iteration at probe time, potentially hundreds of thousands of iterations with recordsize=1. In the final iterations near the BIOS image boundary, struct casts beyond the 2-byte header validated by GETIMAGE can also read out of bounds.

Cap all 14 record-chain walk loops to BIOSMAXNUM_RECORD (256) iterations. The atombios.h defines up to 22 distinct record types and atomfirmware.h has 13. Assuming an average of less than 10 records per type (which is reasonable since most are connector- based) 256 is a generous upper bound.

(cherry picked from commit 95700a3d660287ed657d6892f7be9ffc0e294a93)