From: Guillaume Nault <g.nault@xxxxxxxxxxxx>
commit cdd10c9627496ad25c87ce6394e29752253c69d3 upstream.
If l2tp_tunnel_delete() or l2tp_tunnel_closeall() deletes a session
right after pppol2tp_release() orphaned its socket, then the 'sock'
variable of the pppol2tp_session_close() callback is NULL. Yet the
session is still used by pppol2tp_release().
Therefore we need to take an extra reference in any case, to prevent
l2tp_tunnel_delete() or l2tp_tunnel_closeall() from freeing the session.
Since the pppol2tp_session_close() callback is only set if the session
is associated to a PPPOL2TP socket and that both l2tp_tunnel_delete()
and l2tp_tunnel_closeall() hold the PPPOL2TP socket before calling
pppol2tp_session_close(), we're sure that pppol2tp_session_close() and
pppol2tp_session_destruct() are paired and called in the right order.
So the reference taken by the former will be released by the later.
Signed-off-by: Guillaume Nault <g.nault@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
---
net/l2tp/l2tp_ppp.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index 16b63e60396f..d919b3e6b548 100644
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -437,11 +437,11 @@ static void pppol2tp_session_close(struct l2tp_session *session)
BUG_ON(session->magic != L2TP_SESSION_MAGIC);
- if (sock) {
+ if (sock)
inet_shutdown(sock, SEND_SHUTDOWN);
- /* Don't let the session go away before our socket does */
- l2tp_session_inc_refcount(session);
- }
+
+ /* Don't let the session go away before our socket does */
+ l2tp_session_inc_refcount(session);
}
/* Really kill the session socket. (Called from sock_put() if
--
2.26.0.rc2.310.g2932bb562d-goog
