Subject: [PATCH AUTOSEL 5.14 12/40] netfilter: ip6_tables: zero-initialize fragment offset

From: Sasha Levin <[email-masked]>
Date: Tue, 5 Oct 2021 09:49:51 -0400

From: Jeremy Sowden <[email-masked]>

[ Upstream commit 310e2d43c3ad429c1fba4b175806cf1f55ed73a6 ]

ip6tables only sets the `IP6T_F_PROTO` flag on a rule if a protocol is
specified (`-p tcp`, for example).  However, if the flag is not set,
`ip6_packet_match` doesn't call `ipv6_find_hdr` for the skb, in which
case the fragment offset is left uninitialized and a garbage value is
passed to each matcher.

Signed-off-by: Jeremy Sowden <[email-masked]>
Reviewed-by: Florian Westphal <[email-masked]>
Signed-off-by: Pablo Neira Ayuso <[email-masked]>
Signed-off-by: Sasha Levin <[email-masked]>
---
 net/ipv6/netfilter/ip6_tables.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index de2cf3943b91..a579ea14a69b 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -273,6 +273,7 @@ ip6t_do_table(struct sk_buff *skb,
 	 * things we don't know, ie. tcp syn flag or ports).  If the
 	 * rule is also a fragment-specific rule, non-fragments won't
 	 * match it. */
+	acpar.fragoff = 0;
 	acpar.hotdrop = false;
 	acpar.state   = state;
 
-- 
2.33.0