CVE-2026-43280

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

drm/xe: Add bounds check on pat_index to prevent OOB kernel read in madvise

When user provides a bogus pat_index value through the madvise IOCTL, the xe_pat_index_get_coh_mode() function performs an array access without validating bounds. This allows a malicious user to trigger an out-of-bounds kernel read from the xe->pat.table array.

The vulnerability exists because the validation in madvise_args_are_sane() directly calls xe_pat_index_get_coh_mode(xe, args->pat_index.val) without first checking if pat_index is within [0, xe->pat.n_entries).

Although xe_pat_index_get_coh_mode() has a WARN_ON to catch this in debug builds, it still performs the unsafe array access in production kernels.

v2(Matthew Auld)

• Using array_index_nospec() to mitigate spectre attacks when the value is used

v3(Matthew Auld)

• Put the declarations at the start of the block

(cherry picked from commit 944a3329b05510d55c69c2ef455136e2fc02de29)

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/79f52655567a6471ff3d0d6325ede91bb14461f4
• https://git.kernel.org/stable/c/fbbe32618e97eff81577a01eb7d9adcd64a216d7
• https://git.kernel.org/stable/c/ffba51100ff61792fefbae11ca38ac1987a818dd