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authorHaishuang Yan <yanhaishuang@cmss.chinamobile.com>2016-04-03 22:09:23 +0800
committerDavid S. Miller <davem@davemloft.net>2016-04-04 16:00:28 -0400
commit5745b8232e942abd5e16e85fa9b27cc21324acf0 (patch)
tree1f4905726d49d18faf80fba0551455997f4417ee /net/l2tp/l2tp_ip.c
parent05cf8077e54b20dddb756eaa26f3aeb5c38dd3cf (diff)
downloadlinux-5745b8232e942abd5e16e85fa9b27cc21324acf0.tar.bz2
ipv4: l2tp: fix a potential issue in l2tp_ip_recv
pskb_may_pull() can change skb->data, so we have to load ptr/optr at the right place. Signed-off-by: Haishuang Yan <yanhaishuang@cmss.chinamobile.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/l2tp/l2tp_ip.c')
-rw-r--r--net/l2tp/l2tp_ip.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c
index ec22078b0914..42de4ccd159f 100644
--- a/net/l2tp/l2tp_ip.c
+++ b/net/l2tp/l2tp_ip.c
@@ -123,12 +123,11 @@ static int l2tp_ip_recv(struct sk_buff *skb)
struct l2tp_tunnel *tunnel = NULL;
int length;
- /* Point to L2TP header */
- optr = ptr = skb->data;
-
if (!pskb_may_pull(skb, 4))
goto discard;
+ /* Point to L2TP header */
+ optr = ptr = skb->data;
session_id = ntohl(*((__be32 *) ptr));
ptr += 4;
@@ -156,6 +155,9 @@ static int l2tp_ip_recv(struct sk_buff *skb)
if (!pskb_may_pull(skb, length))
goto discard;
+ /* Point to L2TP header */
+ optr = ptr = skb->data;
+ ptr += 4;
pr_debug("%s: ip recv\n", tunnel->name);
print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length);
}