net/l2tp: Fix reference count leak in l2tp_udp_recv_core

The reference count leak issue may take place in an error handling path. If both conditions of tunnel->version == L2TP_HDR_VER_3 and the return value of l2tp_v3_ensure_opt_in_linear is nonzero, the function would directly jump to label invalid, without decrementing the reference count of the l2tp_session object session increased earlier by l2tp_tunnel_get_session(). This may result in refcount leaks. Fix this issue by decrease the reference count before jumping to the label invalid. Fixes: 4522a70 ("l2tp: fix reading optional fields of L2TPv3") Signed-off-by: Xiyu Yang <[email protected]> Signed-off-by: Xin Xiong <[email protected]> Signed-off-by: Xin Tan <[email protected]> Signed-off-by: David S. Miller <[email protected]>
ambv · Sep 9, 2021 · 9b6ff7e · 9b6ff7e
1 parent 04f08eb
commit 9b6ff7e
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
@@ -869,8 +869,10 @@ static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb)
 	}
 
 	if (tunnel->version == L2TP_HDR_VER_3 &&
-	    l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr))
+	    l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr)) {
+		l2tp_session_dec_refcount(session);
 		goto invalid;
+	}
 
 	l2tp_recv_common(session, skb, ptr, optr, hdrflags, length);
 	l2tp_session_dec_refcount(session);