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 bios_parser.c and bios_parser2.c use for(;;) and only terminate on a 0xFF record_type sentinel or zero record_size. A malformed VBIOS image missing the terminator record causes unbounded iteration at probe time, potentially hundreds of thousands of iterations with record_size=1. In the final iterations near the BIOS image boundary, struct casts beyond the 2-byte header validated by GET_IMAGE can also read out of bounds.

Cap all 14 record-chain walk loops to BIOS_MAX_NUM_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)

Weakness

The product reads data past the end, or before the beginning, of the intended buffer.

Affected Software

Potential Mitigations

• Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
• When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
• Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
• To reduce the likelihood of introducing an out-of-bounds read, ensure that you validate and ensure correct calculations for any length argument, buffer size calculation, or offset. Be especially careful of relying on a sentinel (i.e. special character such as NUL) in untrusted inputs.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/540.html

References

• https://git.kernel.org/stable/c/04e271a952b8863bbafc99bd51aca4c32bff0e0d
• https://git.kernel.org/stable/c/0e56f460bddb397fa9a8e6faf7ae7eaa86953eb1
• https://git.kernel.org/stable/c/2645e3caf7e013189da9c6ff621d006cca5a538b
• https://git.kernel.org/stable/c/499c6b43a79dd684bddbd18fe8b2235aa2764db4
• https://git.kernel.org/stable/c/6173cfea2f916e01c4f98e29cd654384a05e32a3
• https://git.kernel.org/stable/c/6723188c42ca3b34a9fce634d7a0ecc9ccd5cd56
• https://git.kernel.org/stable/c/e94f5323c41f32a74160378c3b19850d1f203ad5
• https://git.kernel.org/stable/c/ff287df16a1a58aca78b08d1f3ee09fc44da0351