sctp: check af before verify address in sctp_addr_id2transport

Commit 6f29a1306131 ("sctp: sctp_addr_id2transport should verify the
addr before looking up assoc") invoked sctp_verify_addr to verify the
addr.

But it didn't check af variable beforehand, once users pass an address
with family = 0 through sockopt, sctp_get_af_specific will return NULL
and NULL pointer dereference will be caused by af->sockaddr_len.

This patch is to fix it by returning NULL if af variable is NULL.

Fixes: 6f29a1306131 ("sctp: sctp_addr_id2transport should verify the addr before looking up assoc")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index e214d2e7e9a30c02847daf354668c42eeaffd0d6..1b5d669e30292a57ed57dd920d81be2a57f97b22 100644 (file)
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -239,7 +239,7 @@ static struct sctp_transport *sctp_addr_id2transport(struct sock *sk,
        union sctp_addr *laddr = (union sctp_addr *)addr;
        struct sctp_transport *transport;
 
-       if (sctp_verify_addr(sk, laddr, af->sockaddr_len))
+       if (!af || sctp_verify_addr(sk, laddr, af->sockaddr_len))
                return NULL;
 
        addr_asoc = sctp_endpoint_lookup_assoc(sctp_sk(sk)->ep,