linux-kernel - [PATCH net] vhost_net: validate sock before trying to put its fd

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Message-Id: <1529557891-4828-1-git-send-email-jasowang@redhat.com>
Date:   Thu, 21 Jun 2018 13:11:31 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     mst@...hat.com, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     dan.carpenter@...cle.com, Jason Wang <jasowang@...hat.com>
Subject: [PATCH net] vhost_net: validate sock before trying to put its fd

Sock will be NULL if we pass -1 to vhost_net_set_backend(), but when
we meet errors during ubuf allocation, the code does not check for
NULL before calling sockfd_put(), this will lead NULL
dereferencing. Fixing by checking sock pointer before.

Fixes: bab632d69ee4 ("vhost: vhost TX zero-copy support")
Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Jason Wang <jasowang@...hat.com>
---
 drivers/vhost/net.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 986058a..b97a994 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -1208,7 +1208,8 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
 	if (ubufs)
 		vhost_net_ubuf_put_wait_and_free(ubufs);
 err_ubufs:
-	sockfd_put(sock);
+	if (sock)
+		sockfd_put(sock);
 err_vq:
 	mutex_unlock(&vq->mutex);
 err:
-- 
2.7.4