From: Jordy Zomer jordy@pwning.systems
[ Upstream commit 5f9c55c8066bcd93ac25234a02585701fe2e31df ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv6/esp6.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/net/ipv6/esp6.c b/net/ipv6/esp6.c index ed2f061b87685..f0bac6f7ab6bb 100644 --- a/net/ipv6/esp6.c +++ b/net/ipv6/esp6.c @@ -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;