CVE-2025-38391

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

usb: typec: altmodes/displayport: do not index invalid pin_assignments

A poorly implemented DisplayPort Alt Mode port partner can indicate that its pin assignment capabilities are greater than the maximum value, DP_PIN_ASSIGN_F. In this case, calls to pin_assignment_show will cause a BRK exception due to an out of bounds array access.

Prevent for loop in pin_assignment_show from accessing invalid values in pin_assignments by adding DP_PIN_ASSIGN_MAX value in typec_dp.h and using i < DP_PIN_ASSIGN_MAX as a loop condition.

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/114a977e0f6bf278e05eade055e13fc271f69cf7
• https://git.kernel.org/stable/c/2f535517b5611b7221ed478527e4b58e29536ddf
• https://git.kernel.org/stable/c/45e9444b3b97eaf51a5024f1fea92f44f39b50c6
• https://git.kernel.org/stable/c/47cb5d26f61d80c805d7de4106451153779297a1
• https://git.kernel.org/stable/c/5581e694d3a1c2f32c5a51d745c55b107644e1f8
• https://git.kernel.org/stable/c/621d5a3ef0231ab242f2d31eecec40c38ca609c5
• https://git.kernel.org/stable/c/af4db5a35a4ef7a68046883bfd12468007db38f1
• https://git.kernel.org/stable/c/c93bc959788ed9a1af7df57cb539837bdf790cee
• https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html
• https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html