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ipv4: l2tp: fix a potential issue in l2tp_ip_recv

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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>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Haishuang Yan 2016-04-03 22:09:23 +08:00 committed by David S. Miller
parent 05cf8077e5
commit 5745b8232e
1 changed files with 5 additions and 3 deletions
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8
net/l2tp/l2tp_ip.c
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@ -123,12 +123,11 @@ static int l2tp_ip_recv(struct sk_buff *skb)
struct l2tp_tunnel *tunnel = NULL; struct l2tp_tunnel *tunnel = NULL;
int length; int length;
/* Point to L2TP header */
optr = ptr = skb->data;
if (!pskb_may_pull(skb, 4)) if (!pskb_may_pull(skb, 4))
goto discard; goto discard;
/* Point to L2TP header */
optr = ptr = skb->data;
session_id = ntohl(*((__be32 *) ptr)); session_id = ntohl(*((__be32 *) ptr));
ptr += 4; ptr += 4;
@ -156,6 +155,9 @@ static int l2tp_ip_recv(struct sk_buff *skb)
if (!pskb_may_pull(skb, length)) if (!pskb_may_pull(skb, length))
goto discard; goto discard;
/* Point to L2TP header */
optr = ptr = skb->data;
ptr += 4;
pr_debug("%s: ip recv\n", tunnel->name); pr_debug("%s: ip recv\n", tunnel->name);
print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length); print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length);
} }