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ipv6: check return value of ipv6_skip_exthdr

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The offset value is used in pointer math on skb->data.
Since ipv6_skip_exthdr may return -1 the pointer to uh and th
may not point to the actual udp and tcp headers and potentially
overwrite other stuff. This is why I think this should be checked.

EDIT:  added {}'s, thanks Kees

Signed-off-by: Jordy Zomer <jordy@pwning.systems>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jordy Zomer 2021-11-17 20:06:48 +01:00 committed by David S. Miller
parent 5d2ca2e12d
commit 5f9c55c806
1 changed files with 6 additions and 0 deletions
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6
net/ipv6/esp6.c
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@ -808,6 +808,12 @@ int esp6_input_done2(struct sk_buff *skb, int err)
struct tcphdr *th;
offset = ipv6_skip_exthdr(skb, offset, &nexthdr, &frag_off);
if (offset < 0) {
err = -EINVAL;
goto out;
}
uh = (void *)(skb->data + offset);
th = (void *)(skb->data + offset);
hdr_len += offset;