From 66d50d25502cd9b7d6e3ebbf4e241259c1283eaf Mon Sep 17 00:00:00 2001 From: stephen hemminger Date: Mon, 2 Aug 2010 13:44:13 +0000 Subject: [PATCH] u32: negative offset fix It was possible to use a negative offset in a u32 match to reference the ethernet header or other parts of the link layer header. This fixes the regression caused by: commit fbc2e7d9cf49e0bf89b9e91fd60a06851a855c5d Author: Changli Gao Date: Wed Jun 2 07:32:42 2010 -0700 cls_u32: use skb_header_pointer() to dereference data safely Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller --- net/sched/cls_u32.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c index 4f522143811e..7416a5c73b2a 100644 --- a/net/sched/cls_u32.c +++ b/net/sched/cls_u32.c @@ -134,10 +134,12 @@ next_knode: #endif for (i = n->sel.nkeys; i>0; i--, key++) { - unsigned int toff; + int toff = off + key->off + (off2 & key->offmask); __be32 *data, _data; - toff = off + key->off + (off2 & key->offmask); + if (skb_headroom(skb) + toff < 0) + goto out; + data = skb_header_pointer(skb, toff, 4, &_data); if (!data) goto out; -- 2.39.5