diff options
authorStefano Brivio <sbrivio@redhat.com>2019-01-03 21:43:35 +0100
committerDavid S. Miller <davem@davemloft.net>2019-01-04 13:06:07 -0800
commit44039e00171b0fe930c07ff7b43e6023eaf1ed31 (patch)
parentbc6e019b6ee65ff4ebf3ca272f774cf6c67db669 (diff)
fou6: Prevent unbounded recursion in GUE error handler
I forgot to deal with IPv6 in commit 11789039da53 ("fou: Prevent unbounded recursion in GUE error handler"). Now syzbot reported what might be the same type of issue, caused by gue6_err(), that is, handling exceptions for direct UDP encapsulation in GUE (UDP-in-UDP) leads to unbounded recursion in the GUE exception handler. As it probably doesn't make sense to set up GUE this way, and it's currently not even possible to configure this, skip exception handling for UDP (or UDP-Lite) packets encapsulated in UDP (or UDP-Lite) packets with GUE on IPv6. Reported-by: syzbot+4ad25edc7a33e4ab91e0@syzkaller.appspotmail.com Reported-by: Willem de Bruijn <willemdebruijn.kernel@gmail.com> Reported-by: Eric Dumazet <eric.dumazet@gmail.com> Fixes: b8a51b38e4d4 ("fou, fou6: ICMP error handlers for FoU and GUE") Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
1 files changed, 8 insertions, 0 deletions
diff --git a/net/ipv6/fou6.c b/net/ipv6/fou6.c
index bd675c61deb1..7da7bf3b7fe3 100644
--- a/net/ipv6/fou6.c
+++ b/net/ipv6/fou6.c
@@ -131,6 +131,14 @@ static int gue6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
if (validate_gue_flags(guehdr, optlen))
return -EINVAL;
+ /* Handling exceptions for direct UDP encapsulation in GUE would lead to
+ * recursion. Besides, this kind of encapsulation can't even be
+ * configured currently. Discard this.
+ */
+ if (guehdr->proto_ctype == IPPROTO_UDP ||
+ guehdr->proto_ctype == IPPROTO_UDPLITE)
+ return -EOPNOTSUPP;
skb_set_transport_header(skb, -(int)sizeof(struct icmp6hdr));
ret = gue6_err_proto_handler(guehdr->proto_ctype, skb,
opt, type, code, offset, info);