From 6e4a2519c9120d058096323649d1d33b91a72b31 Mon Sep 17 00:00:00 2001
From: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Date: Thu, 9 Sep 2021 12:32:00 +0800
Subject: [PATCH] net/l2tp: Fix reference count leak in l2tp_udp_recv_core
Git-commit: 9b6ff7eb666415e1558f1ba8a742f5db6a9954de
Patch-mainline: v5.15-rc2
References: stable-5.14.7
commit 9b6ff7eb666415e1558f1ba8a742f5db6a9954de upstream.
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: 4522a70db7aa ("l2tp: fix reading optional fields of L2TPv3")
Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Xiong <xiongx18@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
net/l2tp/l2tp_core.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index 53486b162f01..93271a2632b8 100644
--- 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);
--
2.26.2