提交 66d50d25 编写于 作者: S stephen hemminger 提交者: David S. Miller

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 fbc2e7d9
Author: Changli Gao <xiaosuo@gmail.com>
Date:   Wed Jun 2 07:32:42 2010 -0700

    cls_u32: use skb_header_pointer() to dereference data safely
Signed-off-by: NStephen Hemminger <shemminger@vyatta.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
上级 eabd8ba9
......@@ -134,10 +134,12 @@ static int u32_classify(struct sk_buff *skb, struct tcf_proto *tp, struct tcf_re
#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;
......
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