Bluetooth: bnep: Fix UAF read of dev->name

bnep_add_connection() needs to keep holding the bnep_session_sem while
reading dev->name (just like bnep_get_connlist() does); otherwise the
bnep_session() thread can concurrently free the net_device, which can for
example be triggered by a concurrent bnep_del_connection().

(This UAF is fairly uninteresting from a security perspective;
calling bnep_add_connection() requires passing a capable(CAP_NET_ADMIN)
check. It also requires completely tearing down a netdev during a fairly
tight race window.)

Cc: stable@vger.kernel.org
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

diff --git a/net/bluetooth/bnep/core.c b/net/bluetooth/bnep/core.c
index 853c8d7644b5580600e9a8c4b5e0f2be4328f726..0de5df690bd0b2bcd0eb667f7460502273ba6636 100644 (file)
--- a/net/bluetooth/bnep/core.c
+++ b/net/bluetooth/bnep/core.c
@@ -645,8 +645,8 @@ int bnep_add_connection(struct bnep_connadd_req *req, struct socket *sock)
                goto failed;
        }
 
-       up_write(&bnep_session_sem);
        strcpy(req->device, dev->name);
+       up_write(&bnep_session_sem);
        return 0;
 
 failed: