Bluetooth: L2CAP: handle NULL sock pointer in l2cap_sock_alloc

A NULL sock pointer is passed into l2cap_sock_alloc() when it is called
from l2cap_sock_new_connection_cb() and the error handling paths should
also be aware of it.

Seemingly a more elegant solution would be to swap bt_sock_alloc() and
l2cap_chan_create() calls since they are not interdependent to that moment
but then l2cap_chan_create() adds the soon to be deallocated and still
dummy-initialized channel to the global list accessible by many L2CAP
paths. The channel would be removed from the list in short period of time
but be a bit more straight-forward here and just check for NULL instead of
changing the order of function calls.

Found by Linux Verification Center (linuxtesting.org) with SVACE static
analysis tool.

Fixes: 7c4f78cdb8e7 ("Bluetooth: L2CAP: do not leave dangling sk pointer on error in l2cap_sock_create()")
Cc: stable@vger.kernel.org
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
index 3d2553dcdb1b3c2869bd86b6dfd03d3e7eed1705..49f97d4138ea71eb7163dda32842732fc39954b7 100644 (file)
--- a/net/bluetooth/l2cap_sock.c
+++ b/net/bluetooth/l2cap_sock.c
@@ -1888,7 +1888,8 @@ static struct sock *l2cap_sock_alloc(struct net *net, struct socket *sock,
        chan = l2cap_chan_create();
        if (!chan) {
                sk_free(sk);
-               sock->sk = NULL;
+               if (sock)
+                       sock->sk = NULL;
                return NULL;
        }