Messages in this thread Patch in this message | | | From | Haishuang Yan <> | Subject | [PATCH 1/2] ipv4: l2tp: fix a potential issue in l2tp_ip_recv | Date | Sun, 3 Apr 2016 22:09:23 +0800 |
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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> --- net/l2tp/l2tp_ip.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c index ec22078..42de4cc 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); } -- 1.8.3.1
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