netdev - [PATCH net v2] netfilter: xt_recent: fix (increase) ipv6 literal buffer length

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Message-Id: <20231105195600.522779-1-maze@google.com>
Date: Sun,  5 Nov 2023 11:56:00 -0800
From: "Maciej Żenczykowski" <maze@...gle.com>
To: "Maciej Żenczykowski" <zenczykowski@...il.com>, "David S . Miller" <davem@...emloft.net>, 
	Pablo Neira Ayuso <pablo@...filter.org>, Florian Westphal <fw@...len.de>
Cc: Linux Network Development Mailing List <netdev@...r.kernel.org>, 
	Netfilter Development Mailing List <netfilter-devel@...r.kernel.org>, Jan Engelhardt <jengelh@...i.de>, 
	Patrick McHardy <kaber@...sh.net>
Subject: [PATCH net v2] netfilter: xt_recent: fix (increase) ipv6 literal
 buffer length

From: Maciej Żenczykowski <zenczykowski@...il.com>

in6_pton() supports 'low-32-bit dot-decimal representation'
(this is useful with DNS64/NAT64 networks for example):

  # echo +aaaa:bbbb:cccc:dddd:eeee:ffff:1.2.3.4 > /proc/self/net/xt_recent/DEFAULT
  # cat /proc/self/net/xt_recent/DEFAULT
  src=aaaa:bbbb:cccc:dddd:eeee:ffff:0102:0304 ttl: 0 last_seen: 9733848829 oldest_pkt: 1 9733848829

but the provided buffer is too short:

  # echo +aaaa:bbbb:cccc:dddd:eeee:ffff:255.255.255.255 > /proc/self/net/xt_recent/DEFAULT
  -bash: echo: write error: Invalid argument

Cc: Jan Engelhardt <jengelh@...i.de>
Cc: Patrick McHardy <kaber@...sh.net>
Fixes: 079aa88fe717 ("netfilter: xt_recent: IPv6 support")
Signed-off-by: Maciej Żenczykowski <zenczykowski@...il.com>
---
 net/netfilter/xt_recent.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/xt_recent.c b/net/netfilter/xt_recent.c
index 7ddb9a78e3fc..ef93e0d3bee0 100644
--- a/net/netfilter/xt_recent.c
+++ b/net/netfilter/xt_recent.c
@@ -561,7 +561,7 @@ recent_mt_proc_write(struct file *file, const char __user *input,
 {
 	struct recent_table *t = pde_data(file_inode(file));
 	struct recent_entry *e;
-	char buf[sizeof("+b335:1d35:1e55:dead:c0de:1715:5afe:c0de")];
+	char buf[sizeof("+b335:1d35:1e55:dead:c0de:1715:255.255.255.255")];
 	const char *c = buf;
 	union nf_inet_addr addr = {};
 	u_int16_t family;
-- 
2.42.0.869.gea05f2083d-goog