From 0528485f27016a42804abe01aa61b39d85fa803e Mon Sep 17 00:00:00 2001 From: Xin Long Date: Fri, 10 Jul 2026 14:12:35 -0400 Subject: [PATCH] sctp: fix auth_hmacs array size in struct sctp_cookie [ Upstream commit e0b5252a59383b77d1b8dbeda00b7184dd95f4d3 ] 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. Fixes: 1f485649f529 ("[SCTP]: Implement SCTP-AUTH internals") Reported-by: Yuan Tan Reported-by: Xin Liu Reported-by: Zihan Xi Reported-by: Ren Wei Signed-off-by: Xin Long Link: https://patch.msgid.link/634a0de0d5de29532915e6d47c92a0cbc206e03f.1783707155.git.lucien.xin@gmail.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- include/net/sctp/structs.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h index b73eadf644b3..c9a811a3248f 100644 --- a/include/net/sctp/structs.h +++ b/include/net/sctp/structs.h @@ -322,7 +322,8 @@ struct sctp_cookie { __u8 auth_random[sizeof(struct sctp_paramhdr) + SCTP_AUTH_RANDOM_LENGTH]; - __u8 auth_hmacs[SCTP_AUTH_NUM_HMACS * sizeof(__u16) + 2]; + __u8 auth_hmacs[sizeof(struct sctp_paramhdr) + + SCTP_AUTH_NUM_HMACS * sizeof(__u16)]; __u8 auth_chunks[sizeof(struct sctp_paramhdr) + SCTP_AUTH_MAX_CHUNKS]; /* This is a shim for my peer's INIT packet, followed by