linux-kernel - [PATCH 17/22] platform/x86: alienware-wmi: fix format string overflow warning

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Message-Id: <20170714120720.906842-18-arnd@arndb.de>
Date:   Fri, 14 Jul 2017 14:07:09 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     linux-kernel@...r.kernel.org, Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Guenter Roeck <linux@...ck-us.net>, akpm@...ux-foundation.org,
        netdev@...r.kernel.org, "David S . Miller" <davem@...emloft.net>,
        "James E . J . Bottomley" <jejb@...ux.vnet.ibm.com>,
        "Martin K . Petersen" <martin.petersen@...cle.com>,
        linux-scsi@...r.kernel.org, x86@...nel.org,
        Arnd Bergmann <arnd@...db.de>,
        Mario Limonciello <mario.limonciello@...l.com>,
        Arvind Yadav <arvind.yadav.cs@...il.com>,
        platform-driver-x86@...r.kernel.org
Subject: [PATCH 17/22] platform/x86: alienware-wmi: fix format string overflow warning

gcc points out a possible format string overflow for a large value of 'zone':

drivers/platform/x86/alienware-wmi.c: In function 'alienware_wmi_init':
drivers/platform/x86/alienware-wmi.c:461:24: error: '%02X' directive writing between 2 and 8 bytes into a region of size 6 [-Werror=format-overflow=]
   sprintf(buffer, "zone%02X", i);
                        ^~~~
drivers/platform/x86/alienware-wmi.c:461:19: note: directive argument in the range [0, 2147483646]
   sprintf(buffer, "zone%02X", i);
                   ^~~~~~~~~~
drivers/platform/x86/alienware-wmi.c:461:3: note: 'sprintf' output between 7 and 13 bytes into a destination of size 10

While the zone should never be that large, it's easy to make the
buffer a few bytes longer so gcc can prove this to be safe.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/platform/x86/alienware-wmi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/platform/x86/alienware-wmi.c b/drivers/platform/x86/alienware-wmi.c
index 0831b428c217..acc01242da82 100644
--- a/drivers/platform/x86/alienware-wmi.c
+++ b/drivers/platform/x86/alienware-wmi.c
@@ -421,7 +421,7 @@ static DEVICE_ATTR(lighting_control_state, 0644, show_control_state,
 static int alienware_zone_init(struct platform_device *dev)
 {
 	int i;
-	char buffer[10];
+	char buffer[13];
 	char *name;
 
 	if (interface == WMAX) {
-- 
2.9.0