From: Martin Schiller <ms@xxxxxxxxxx> commit e21dba7a4df4d93da237da65a096084b4f2e87b4 upstream. This patch fixes 2 issues in x25_connect(): 1. It makes absolutely no sense to reset the neighbour and the connection state after a (successful) nonblocking call of x25_connect. This prevents any connection from being established, since the response (call accept) cannot be processed. 2. Any further calls to x25_connect() while a call is pending should simply return, instead of creating new Call Request (on different logical channels). This patch should also fix the "KASAN: null-ptr-deref Write in x25_connect" and "BUG: unable to handle kernel NULL pointer dereference in x25_connect" bugs reported by syzbot. Signed-off-by: Martin Schiller <ms@xxxxxxxxxx> Reported-by: syzbot+429c200ffc8772bfe070@xxxxxxxxxxxxxxxxxxxxxxxxx Reported-by: syzbot+eec0c87f31a7c3b66f7b@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/x25/af_x25.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) --- a/net/x25/af_x25.c +++ b/net/x25/af_x25.c @@ -764,6 +764,10 @@ static int x25_connect(struct socket *so if (sk->sk_state == TCP_ESTABLISHED) goto out; + rc = -EALREADY; /* Do nothing if call is already in progress */ + if (sk->sk_state == TCP_SYN_SENT) + goto out; + sk->sk_state = TCP_CLOSE; sock->state = SS_UNCONNECTED; @@ -810,7 +814,7 @@ static int x25_connect(struct socket *so /* Now the loop */ rc = -EINPROGRESS; if (sk->sk_state != TCP_ESTABLISHED && (flags & O_NONBLOCK)) - goto out_put_neigh; + goto out; rc = x25_wait_for_connection_establishment(sk); if (rc)
