5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Xin Long lucien.xin@gmail.com
[ 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... Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/sctp/socket.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/net/sctp/socket.c b/net/sctp/socket.c index 614130ff6ba06..eef807edd61da 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -8396,8 +8396,10 @@ 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);