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authorHerbert Xu <herbert@gondor.apana.org.au>2008-09-30 02:03:19 -0700
committerDavid S. Miller <davem@davemloft.net>2008-09-30 02:03:19 -0700
commitd01dbeb6af7a0848063033f73c3d146fec7451f3 (patch)
tree7b912030e10097483843c0dfa006e3793e31c9ae
parent94aca1dac6f6d21f4b07e4864baf7768cabcc6e7 (diff)
downloadlinux-d01dbeb6af7a0848063033f73c3d146fec7451f3.tar.gz
ipsec: Fix pskb_expand_head corruption in xfrm_state_check_space
We're never supposed to shrink the headroom or tailroom.  In fact,
shrinking the headroom is a fatal action.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/xfrm/xfrm_output.c12
1 files changed, 8 insertions, 4 deletions
diff --git a/net/xfrm/xfrm_output.c b/net/xfrm/xfrm_output.c
index ac25b4c0e982..dc50f1e71f76 100644
--- a/net/xfrm/xfrm_output.c
+++ b/net/xfrm/xfrm_output.c
@@ -27,10 +27,14 @@ static int xfrm_state_check_space(struct xfrm_state *x, struct sk_buff *skb)
 		- skb_headroom(skb);
 	int ntail = dst->dev->needed_tailroom - skb_tailroom(skb);
 
-	if (nhead > 0 || ntail > 0)
-		return pskb_expand_head(skb, nhead, ntail, GFP_ATOMIC);
-
-	return 0;
+	if (nhead <= 0) {
+		if (ntail <= 0)
+			return 0;
+		nhead = 0;
+	} else if (ntail < 0)
+		ntail = 0;
+
+	return pskb_expand_head(skb, nhead, ntail, GFP_ATOMIC);
 }
 
 static int xfrm_output_one(struct sk_buff *skb, int err)