linux-kernel - Re: [PATCH] dell-smbios: fix string overflow

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Message-ID: <20171108204533.GA21449@fury>
Date:   Wed, 8 Nov 2017 12:45:33 -0800
From:   Darren Hart <dvhart@...radead.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Pali Rohár <pali.rohar@...il.com>,
        Mario Limonciello <mario.limonciello@...l.com>,
        Andy Shevchenko <andy@...radead.org>,
        Edward O'Callaghan <quasisec@...gle.com>,
        Hans de Goede <hdegoede@...hat.com>,
        platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dell-smbios: fix string overflow

On Wed, Nov 08, 2017 at 01:08:39PM +0100, Arnd Bergmann wrote:
> The new sysfs code overwrites two fixed-length character arrays
> that are each one byte shorter than they need to be, to hold
> the trailing \0:
> 
> drivers/platform/x86/dell-smbios.c: In function 'build_tokens_sysfs':
> drivers/platform/x86/dell-smbios.c:494:42: error: 'sprintf' writing a terminating nul past the end of the destination [-Werror=format-overflow=]
>    sprintf(buffer_location, "%04x_location",
> drivers/platform/x86/dell-smbios.c:494:3: note: 'sprintf' output 14 bytes into a destination of size 13
> drivers/platform/x86/dell-smbios.c:506:36: error: 'sprintf' writing a terminating nul past the end of the destination [-Werror=format-overflow=]
>    sprintf(buffer_value, "%04x_value",
> drivers/platform/x86/dell-smbios.c:506:3: note: 'sprintf' output 11 bytes into a destination of size 10
> 
> This changes it to just use kasprintf(), which always gets it right.
> 
> Fixes: 33b9ca1e53b4 ("platform/x86: dell-smbios: Add a sysfs interface for SMBIOS tokens")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>


Queued, thanks Arnd.

Yes, please keep the error messages. Costs us nothing and can be useful to have.

I corrected the prefix as noted, and added the details of the gcc and reverted
patch for reproducer context.

-- 
Darren Hart
VMware Open Source Technology Center