diff mbox series

[15/27] l2tp: initialise session's refcount before making it reachable

Message ID 20200521235740.191338-16-gprocida@google.com
State New
Headers show
Series [01/27] l2tp: lock socket before checking flags in connect() | expand

Commit Message

Giuliano Procida May 21, 2020, 11:57 p.m. UTC 
From: Guillaume Nault <g.nault@alphalink.fr>

commit 9ee369a405c57613d7c83a3967780c3e30c52ecc upstream.

Sessions must be fully initialised before calling
l2tp_session_add_to_tunnel(). Otherwise, there's a short time frame
where partially initialised sessions can be accessed by external users.

Backporting Notes

l2tp_core.c: moving code that had been converted from atomic to
refcount_t by an earlier change (which isn't being included in this
patch series).

Fixes: dbdbc73b4478 ("l2tp: fix duplicate session creation")
Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Giuliano Procida <gprocida@google.com>
---
 net/l2tp/l2tp_core.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index 7e593e399774..c0abd5efd824 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -1853,6 +1853,8 @@  struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunn
 
 		l2tp_session_set_header_len(session, tunnel->version);
 
+		l2tp_session_inc_refcount(session);
+
 		err = l2tp_session_add_to_tunnel(tunnel, session);
 		if (err) {
 			kfree(session);
@@ -1860,10 +1862,6 @@  struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunn
 			return ERR_PTR(err);
 		}
 
-		/* Bump the reference count. The session context is deleted
-		 * only when this drops to zero.
-		 */
-		l2tp_session_inc_refcount(session);
 		l2tp_tunnel_inc_refcount(tunnel);
 
 		/* Ensure tunnel socket isn't deleted */