linux-kernel - [RFC 4/7] drivers/media/pci/zoran: avoid fragile snprintf use

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Message-Id: <1457469654-17059-5-git-send-email-linux@rasmusvillemoes.dk>
Date:	Tue,  8 Mar 2016 21:40:51 +0100
From:	Rasmus Villemoes <linux@...musvillemoes.dk>
To:	Kees Cook <keescook@...omium.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Mauro Carvalho Chehab <mchehab@....samsung.com>
Cc:	Rasmus Villemoes <linux@...musvillemoes.dk>,
	mjpeg-users@...ts.sourceforge.net, linux-media@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [RFC 4/7] drivers/media/pci/zoran: avoid fragile snprintf use

Appending to a string by doing snprintf(buf, bufsize, "%s...", buf,
...) is not guaranteed to work.

Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>
---
 drivers/media/pci/zoran/videocodec.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/media/pci/zoran/videocodec.c b/drivers/media/pci/zoran/videocodec.c
index c01071635290..13a3c07cd259 100644
--- a/drivers/media/pci/zoran/videocodec.c
+++ b/drivers/media/pci/zoran/videocodec.c
@@ -116,8 +116,9 @@ videocodec_attach (struct videocodec_master *master)
 				goto out_module_put;
 			}
 
-			snprintf(codec->name, sizeof(codec->name),
-				 "%s[%d]", codec->name, h->attached);
+			res = strlen(codec->name);
+			snprintf(codec->name + res, sizeof(codec->name) - res,
+				 "[%d]", h->attached);
 			codec->master_data = master;
 			res = codec->setup(codec);
 			if (res == 0) {
-- 
2.1.4