netdev - [PATCH] net/vmw_vsock: fix NULL pointer deref and improve locking

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <trinity-64b93de7-52ac-4127-a29a-1a6dbbb7aeb6-1612474127915@3c-app-gmx-bap39>
Date:   Thu, 4 Feb 2021 22:28:47 +0100
From:   Norbert Slusarek <nslusarek@....net>
To:     Stefano Garzarella <sgarzare@...hat.com>, alex.popov@...ux.com,
        kuba@...nel.org
Cc:     netdev@...r.kernel.org
Subject: [PATCH] net/vmw_vsock: fix NULL pointer deref and improve locking

From: Norbert Slusarek <nslusarek@....net>
Date: Thu, 4 Feb 2021 18:49:24 +0100
Subject: [PATCH] net/vmw_vsock: fix NULL pointer deref and improve locking

In vsock_stream_connect(), a thread will enter schedule_timeout().
While being scheduled out, another thread can enter vsock_stream_connect() as
well and set vsk->transport to NULL. In case a signal was sent, the first
thread can leave schedule_timeout() and vsock_transport_cancel_pkt() will be
called right after. Inside vsock_transport_cancel_pkt(), a null dereference
will happen on transport->cancel_pkt.

The patch also features improved locking inside vsock_connect_timeout().

Signed-off-by: Norbert Slusarek <nslusarek@....net>
---
 net/vmw_vsock/af_vsock.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 3b480ed0953a..ea7b9d208724 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -1233,7 +1233,7 @@ static int vsock_transport_cancel_pkt(struct vsock_sock *vsk)
 {
 	const struct vsock_transport *transport = vsk->transport;

-	if (!transport->cancel_pkt)
+	if (!transport || !transport->cancel_pkt)
 		return -EOPNOTSUPP;

 	return transport->cancel_pkt(vsk);
@@ -1243,7 +1243,6 @@ static void vsock_connect_timeout(struct work_struct *work)
 {
 	struct sock *sk;
 	struct vsock_sock *vsk;
-	int cancel = 0;

 	vsk = container_of(work, struct vsock_sock, connect_work.work);
 	sk = sk_vsock(vsk);
@@ -1254,11 +1253,9 @@ static void vsock_connect_timeout(struct work_struct *work)
 		sk->sk_state = TCP_CLOSE;
 		sk->sk_err = ETIMEDOUT;
 		sk->sk_error_report(sk);
-		cancel = 1;
+		vsock_transport_cancel_pkt(vsk);
 	}
 	release_sock(sk);
-	if (cancel)
-		vsock_transport_cancel_pkt(vsk);

 	sock_put(sk);
 }
--
2.30.0