From aa8673599f1d269b4e4d9b0c0f61fca57bc02699 Mon Sep 17 00:00:00 2001
From: "David S. Miller" <davem@davemloft.net>
Date: Mon, 11 Apr 2011 18:59:05 -0700
Subject: [PATCH] llc: Fix length check in llc_fixup_skb().

Fixes bugzilla #32872

The LLC stack pretends to support non-linear skbs but there is a
direct use of skb_tail_pointer() in llc_fixup_skb().

Use pskb_may_pull() to see if data_size bytes remain and can be
accessed linearly in the packet, instead of direct pointer checks.

Signed-off-by: David S. Miller <davem@davemloft.net>
---
 net/llc/llc_input.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/net/llc/llc_input.c b/net/llc/llc_input.c
index 058f1e9a91281..903242111317f 100644
--- a/net/llc/llc_input.c
+++ b/net/llc/llc_input.c
@@ -121,8 +121,7 @@ static inline int llc_fixup_skb(struct sk_buff *skb)
 		s32 data_size = ntohs(pdulen) - llc_len;
 
 		if (data_size < 0 ||
-		    ((skb_tail_pointer(skb) -
-		      (u8 *)pdu) - llc_len) < data_size)
+		    !pskb_may_pull(skb, data_size))
 			return 0;
 		if (unlikely(pskb_trim_rcsum(skb, data_size)))
 			return 0;