From: Martin Schiller <ms@dev.tdt.de>
To: arnd@arndb.de, davem@davemloft.net
Cc: andrew.hendry@gmail.com, edumazet@google.com,
gregkh@linuxfoundation.org, tglx@linutronix.de,
linux-x25@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com,
Martin Schiller <ms@dev.tdt.de>,
syzbot+429c200ffc8772bfe070@syzkaller.appspotmail.com,
syzbot+eec0c87f31a7c3b66f7b@syzkaller.appspotmail.com
Subject: [PATCH] net/x25: fix nonblocking connect
Date: Thu, 9 Jan 2020 07:31:14 +0100 [thread overview]
Message-ID: <20200109063114.23195-1-ms@dev.tdt.de> (raw)
In-Reply-To: <CAK8P3a0LdF+aQ1hnZrVKkNBQaum0WqW1jyR7_Eb+JRiwyHWr6Q@mail.gmail.com>
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
---
net/x25/af_x25.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c
index 2efe44a34644..d5b09bbff375 100644
--- a/net/x25/af_x25.c
+++ b/net/x25/af_x25.c
@@ -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)
--
2.20.1
next prev parent reply other threads:[~2020-01-09 6:31 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-06 9:31 KASAN: null-ptr-deref Write in x25_connect syzbot
2019-12-06 12:41 ` Arnd Bergmann
2020-01-09 6:31 ` Martin Schiller [this message]
2020-01-10 2:40 ` [PATCH] net/x25: fix nonblocking connect David Miller
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