High [CVE-2026-68376] fix auth_hmacs array size in struct sctp_cookie

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().

A flaw was found in the Linux kernel's Stream Control Transmission Protocol (SCTP) implementation. An incorrect array size calculation for the `auth_hmacs` field within the `sctp_cookie` structure could lead to a buffer overflow.

During the initialization of an SCTP association, if four HMAC identifiers are configured, the system attempts to copy data beyond the allocated buffer. This results in the corruption of an adjacent memory field (`auth_chunks`) and can subsequently cause an out-of-bounds read when processing HMAC identifiers.