linux-kernel - [PATCH 1/7] Handle snprintf calculations in x

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Message-ID: <ecc58bca-b180-df34-339a-cb278205086c@x41-dsec.de>
Date:   Wed, 11 Oct 2017 10:28:22 +0200
From:   Eric Sesterhenn <eric.sesterhenn@...-dsec.de>
To:     linux-kernel@...r.kernel.org
Subject: [PATCH 1/7] Handle snprintf calculations in x_tables


Handle the snprintf calculations more gracefully in case snprintf
truncates the string.

Signed-off-by: Eric Sesterhenn <eric.sesterhenn@...-dsec.de>
---
 net/netfilter/x_tables.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index c83a3b5e1c6c..327617acbf05 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -408,6 +408,8 @@ textify_hooks(char *buf, size_t size, unsigned int
mask, uint8_t nfproto)
 		if (!(mask & (1 << i)))
 			continue;
 		res = snprintf(p, size, "%s%s", np ? "/" : "", names[i]);
+		if (res >= size)
+			return buf;
 		if (res > 0) {
 			size -= res;
 			p += res;

-- 
Eric Sesterhenn (Principal Security Consultant)
X41 D-SEC GmbH, Dennewartstr. 25-27, D-52068 Aachen
T: +49 241 9809418-0, Fax: -9
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