linux-kernel - Re: [PATCH 19/22] block: DAC960: shut up format-overflow warning

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Message-ID: <8d2a77af-525b-5e95-03e9-bf897e96b846@fb.com>
Date:   Fri, 14 Jul 2017 08:04:31 -0600
From:   Jens Axboe <axboe@...com>
To:     Arnd Bergmann <arnd@...db.de>, <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
CC:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Guenter Roeck <linux@...ck-us.net>, <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>,
        Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
Subject: Re: [PATCH 19/22] block: DAC960: shut up format-overflow warning

On 07/14/2017 06:07 AM, Arnd Bergmann wrote:
> gcc-7 points out that a large controller number would overflow the
> string length for the procfs name and the firmware version string:
> 
> drivers/block/DAC960.c: In function 'DAC960_Probe':
> drivers/block/DAC960.c:6591:38: warning: 'sprintf' may write a terminating nul past the end of the destination [-Wformat-overflow=]
> drivers/block/DAC960.c: In function 'DAC960_V1_ReadControllerConfiguration':
> drivers/block/DAC960.c:1681:40: error: '%02d' directive writing between 2 and 3 bytes into a region of size between 2 and 5 [-Werror=format-overflow=]
> drivers/block/DAC960.c:1681:40: note: directive argument in the range [0, 255]
> drivers/block/DAC960.c:1681:3: note: 'sprintf' output between 10 and 14 bytes into a destination of size 12
> 
> Both of these seem appropriately sized, and using snprintf()
> instead of sprintf() improves this by ensuring that even
> incorrect data won't cause undefined behavior here.

Thanks Arnd, added for 4.14.

-- 
Jens Axboe