| From | Luis Henriques <> | Subject | [PATCH 3.16.y-ckt 093/104] l2tp: protect tunnel->del_work by ref_count | Date | Mon, 26 Oct 2015 13:43:15 +0000 |
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3.16.7-ckt19 -stable review patch. If anyone has any objections, please let me know.
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From: Alexander Couzens <lynxis@fe80.eu>
commit 06a15f51cf3618e32a73871ee6a547ef7fd902b5 upstream.
There is a small chance that tunnel_free() is called before tunnel->del_work scheduled resulting in a zero pointer dereference.
Signed-off-by: Alexander Couzens <lynxis@fe80.eu> Acked-by: James Chapman <jchapman@katalix.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- net/l2tp/l2tp_core.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c index bea259043205..0c6a8f18b0fc 100644 --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -1318,7 +1318,7 @@ static void l2tp_tunnel_del_work(struct work_struct *work) tunnel = container_of(work, struct l2tp_tunnel, del_work); sk = l2tp_tunnel_sock_lookup(tunnel); if (!sk) - return; + goto out; sock = sk->sk_socket; @@ -1339,6 +1339,8 @@ static void l2tp_tunnel_del_work(struct work_struct *work) } l2tp_tunnel_sock_put(sk); +out: + l2tp_tunnel_dec_refcount(tunnel); } /* Create a socket for the tunnel, if one isn't set up by @@ -1673,8 +1675,13 @@ EXPORT_SYMBOL_GPL(l2tp_tunnel_create); */ int l2tp_tunnel_delete(struct l2tp_tunnel *tunnel) { + l2tp_tunnel_inc_refcount(tunnel); l2tp_tunnel_closeall(tunnel); - return (false == queue_work(l2tp_wq, &tunnel->del_work)); + if (false == queue_work(l2tp_wq, &tunnel->del_work)) { + l2tp_tunnel_dec_refcount(tunnel); + return 1; + } + return 0; } EXPORT_SYMBOL_GPL(l2tp_tunnel_delete);
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