CVE-2026-68277drm/dp/mst: fix OOB reads on 2-byte fields in sideband reply parsers

Official description

In the Linux kernel, the following vulnerability has been resolved: drm/dp/mst: fix OOB reads on 2-byte fields in sideband reply parsers Three sideband reply parsers read 16-bit fields as: val = (raw->msg[idx] << 8) | (raw->msg[idx+1]); and check bounds only after the fact. When idx == raw->curlen, raw->msg[idx+1] reads one byte past the received message data into the following struct fields (curchunk_len, curchunk_idx, curlen). Affected functions: - drm_dp_sideband_parse_enum_path_resources_ack() full_payload_bw_number and avail_payload_bw_number fields - drm_dp_sideband_parse_allocate_payload_ack() allocated_pbn field - drm_dp_sideband_parse_query_payload_ack() allocated_pbn field Fix by using a single combined check (idx + 2 > curlen) before each 2-byte read. Since the check is strictly tighter than idx > curlen, no separate step is needed. [added fixes tag]

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/c1f72a13d54ffd16647d3fa540d961f5deba8790
• https://git.kernel.org/stable/c/192e146c2d57ad033b0d418ec64ee390f8dc074e
• https://git.kernel.org/stable/c/6e3107e6522109a07fc9bb0fc4ec463f1982e113
• https://git.kernel.org/stable/c/bdf0508b1e6785d4a8982c637e97e68d60b47d7b
• https://git.kernel.org/stable/c/0bcd7675c69a2462a8531fcd9e4d096e9c7ec5df
• https://git.kernel.org/stable/c/d5c70523cafa26ad2c7a37b612849abe2683baa8
• https://git.kernel.org/stable/c/68a624416d1dd481b3e5b7ea0e8a070a9b8a2c73
• https://git.kernel.org/stable/c/6b89ba3dba2f583626fb693e47e951ffb8bf591f