In the Linux kernel, the following vulnerability has been resolved:
sctp: auth: verify auth requirement when auth_chunk is NULL
sctp_auth_chunk_verify() returns true unconditionally when chunk->auth_chunk is NULL, silently skipping authentication. This is incorrect when:
skb_clone() failed in the BH receive path, leaving auth_chunk NULL. In sctp_endpoint_bh_rcv() asoc is NULL for new connections, so the early sctp_auth_recv_cid() check cannot catch this.
No AUTH chunk precedes COOKIE-ECHO, so skb_clone() is never called and auth_chunk remains NULL.
Fix by checking sctp_auth_recv_cid() when auth_chunk is NULL: if authentication is required, return false to drop the chunk; otherwise continue normally.
References
- https://git.kernel.org/stable/c/18957373920caf5cdaf5cf32e5d1d7a99ca7700a
- https://git.kernel.org/stable/c/28c5fdce9dd955d2baf5e28987819b6d7cfaf646
- https://git.kernel.org/stable/c/83f5031f2a6a49d696eb4cc0898345d12f9c6451
- https://git.kernel.org/stable/c/8e04823c120b376ef7dab14b60ebf6823aa16c14
- https://git.kernel.org/stable/c/ec2e157fc9678a9bc411305a25aec3fd337d7efb