CVE-2026-68376sctp: fix auth_hmacs array size in struct sctp_cookie

Official description

In the Linux kernel, the following vulnerability has been resolved: sctp: fix auth_hmacs array size in struct sctp_cookie The auth_hmacs array in struct sctp_cookie is supposed to store a complete SCTP_AUTH_HMAC_ALGO parameter, which consists of a struct sctp_paramhdr followed by N HMAC identifiers. However, the array size was calculated using an extra 2 bytes instead of sizeof(struct sctp_paramhdr), which is 4 bytes. When four HMAC identifiers are configured, the HMAC-ALGO parameter stored in the endpoint is larger than the auth_hmacs buffer in the cookie. As a result, sctp_association_init() copies beyond the end of auth_hmacs when initializing the association, corrupting the adjacent auth_chunks field. This can lead to an invalid HMAC identifier being accepted and later cause an out-of-bounds read in sctp_auth_get_hmac(). Fix the array size calculation by including the full SCTP parameter header size.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/317731d01b03c529809df36d3a7d149677a8729d
• https://git.kernel.org/stable/c/0528485f27016a42804abe01aa61b39d85fa803e
• https://git.kernel.org/stable/c/ee5e65964f456adfe14d526fba0bd055de98ecf3
• https://git.kernel.org/stable/c/0b4414e43e0861d67276031cc21401d7e87de3da
• https://git.kernel.org/stable/c/d0a59ba58578e2b330fff80a44fe519f3ba7d8c7
• https://git.kernel.org/stable/c/a8d20ba0ab518c9ccbcde258f25fc1ee6e51d5db
• https://git.kernel.org/stable/c/3aa40c3bccac2312ea7cf97f329190637f972b5d
• https://git.kernel.org/stable/c/e0b5252a59383b77d1b8dbeda00b7184dd95f4d3