From 9bd8af9979f543fb605fbfb79e0e8ceeffb88c9c Mon Sep 17 00:00:00 2001 From: Haishuang Yan Date: Sun, 3 Apr 2016 22:09:24 +0800 Subject: [PATCH] ipv6: l2tp: fix a potential issue in l2tp_ip6_recv [ Upstream commit be447f305494e019dfc37ea4cdf3b0e4200b4eba ] pskb_may_pull() can change skb->data, so we have to load ptr/optr at the right place. Signed-off-by: Haishuang Yan Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/l2tp/l2tp_ip6.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/net/l2tp/l2tp_ip6.c b/net/l2tp/l2tp_ip6.c index a2c8747d2936..9ee4ddb6b397 100644 --- a/net/l2tp/l2tp_ip6.c +++ b/net/l2tp/l2tp_ip6.c @@ -135,12 +135,11 @@ static int l2tp_ip6_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; @@ -168,6 +167,9 @@ static int l2tp_ip6_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); } -- 2.34.1