netdev - [PATCH net 03/15] netfilter: ip6_tables: zero-initialize fragment offset

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Message-Id: <20210924221113.348767-4-pablo@netfilter.org>
Date:   Sat, 25 Sep 2021 00:11:01 +0200
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     netfilter-devel@...r.kernel.org
Cc:     davem@...emloft.net, netdev@...r.kernel.org, kuba@...nel.org
Subject: [PATCH net 03/15] netfilter: ip6_tables: zero-initialize fragment offset

From: Jeremy Sowden <jeremy@...zel.net>

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 <jeremy@...zel.net>
Reviewed-by: Florian Westphal <fw@...len.de>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 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;
 
-- 
2.30.2