Commit c4efc614 authored Jan 09, 2020 by Martin Schiller Committed by Greg Kroah-Hartman Jan 29, 2020

net/x25: fix nonblocking connect



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@dev.tdt.de>
Reported-by:  <syzbot+429c200ffc8772bfe070@syzkaller.appspotmail.com>
Reported-by:  <syzbot+eec0c87f31a7c3b66f7b@syzkaller.appspotmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 1bbbcf6d

net/x25/af_x25.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -764,6 +764,10 @@ static int x25_connect(struct socket sock, struct sockaddr uaddr,
		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 sock, struct sockaddr uaddr,
		/* 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)