sctp: set sk_state back to CLOSED if autobind fails in sctp_listen_start

[ Upstream commit 8beee4d8dee76b67c75dc91fd8185d91e845c160 ]

In sctp_listen_start() invoked by sctp_inet_listen(), it should set the
sk_state back to CLOSED if sctp_autobind() fails due to whatever reason.

Otherwise, next time when calling sctp_inet_listen(), if sctp_sk(sk)->reuse
is already set via setsockopt(SCTP_REUSE_PORT), sctp_sk(sk)->bind_hash will
be dereferenced as sk_state is LISTENING, which causes a crash as bind_hash
is NULL.

  KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
  RIP: 0010:sctp_inet_listen+0x7f0/0xa20 net/sctp/socket.c:8617
  Call Trace:
   <TASK>
   __sys_listen_socket net/socket.c:1883 [inline]
   __sys_listen+0x1b7/0x230 net/socket.c:1894
   __do_sys_listen net/socket.c:1902 [inline]

Fixes: 5e8f3f703ae4 ("sctp: simplify sctp listening code")
Reported-by: syzbot+f4e0f821e3a3b7cee51d@syzkaller.appspotmail.com
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Link: https://patch.msgid.link/a93e655b3c153dc8945d7a812e6d8ab0d52b7aa0.1727729391.git.lucien.xin@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index c009383369b2671b1be8c220a9b2082b59209bd2..cefac9eaddc30029741d7be11cd482c1c1c71863 100644 (file)
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -8552,8 +8552,10 @@ static int sctp_listen_start(struct sock *sk, int backlog)
         */
        inet_sk_set_state(sk, SCTP_SS_LISTENING);
        if (!ep->base.bind_addr.port) {
-               if (sctp_autobind(sk))
+               if (sctp_autobind(sk)) {
+                       inet_sk_set_state(sk, SCTP_SS_CLOSED);
                        return -EAGAIN;
+               }
        } else {
                if (sctp_get_port(sk, inet_sk(sk)->inet_num)) {
                        inet_sk_set_state(sk, SCTP_SS_CLOSED);