CVE-2026-68376

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.