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net/x25: fix nonblocking connect

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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>
This commit is contained in:
Martin Schiller 2020-01-09 07:31:14 +01:00 committed by David S. Miller
parent 3249b1e442
commit e21dba7a4d
1 changed files with 5 additions and 1 deletions
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6
net/x25/af_x25.c
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@ -766,6 +766,10 @@ 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;
@ -812,7 +816,7 @@ 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)