linux-kernel - [PATCH] netfilter: Don't parse CTCP message if shorter than minimum length

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Message-ID: <20230621032953.107143-1-sohomdatta1+git@gmail.com>
Date:   Tue, 20 Jun 2023 23:29:53 -0400
From:   Sohom <sohomdatta1@...il.com>
To:     Pablo Neira Ayuso <pablo@...filter.org>,
        Jozsef Kadlecsik <kadlec@...filter.org>,
        Florian Westphal <fw@...len.de>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Cc:     Sohom <sohomdatta1+git@...il.com>, netfilter-devel@...r.kernel.org,
        coreteam@...filter.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] netfilter: Don't parse CTCP message if shorter than minimum length

If the CTCP message is shorter than 10 + 21 + MINMATCHLEN
then exit early and don't parse the rest of the message.

Signed-off-by: Sohom <sohomdatta1+git@...il.com>
---
 net/netfilter/nf_conntrack_irc.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nf_conntrack_irc.c b/net/netfilter/nf_conntrack_irc.c
index 5703846bea3b..703b5a123cb5 100644
--- a/net/netfilter/nf_conntrack_irc.c
+++ b/net/netfilter/nf_conntrack_irc.c
@@ -157,8 +157,12 @@ static int help(struct sk_buff *skb, unsigned int protoff,
 	data = ib_ptr;
 	data_limit = ib_ptr + datalen;
 
+	if (data >= data_limit - (10 + 21 + MINMATCHLEN)) {
+		goto out;
+	}
+
 	/* Skip any whitespace */
-	while (data < data_limit - 10) {
+	while (data < data_limit) {
 		if (*data == ' ' || *data == '\r' || *data == '\n')
 			data++;
 		else
-- 
2.41.0