Messages in this thread Patch in this message | | | From | Jordy Zomer <> | Subject | [PATCH] ipv6: check return value of ipv6_skip_exthdr | Date | Wed, 17 Nov 2021 19:16:10 +0100 |
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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.
Signed-off-by: Jordy Zomer <jordy@pwning.systems> --- net/ipv6/esp6.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/net/ipv6/esp6.c b/net/ipv6/esp6.c index ed2f061b8768..dc4251655df9 100644 --- a/net/ipv6/esp6.c +++ b/net/ipv6/esp6.c @@ -808,6 +808,11 @@ 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; -- 2.27.0
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