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

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Date:   Wed, 8 Nov 2017 21:01:26 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     sathyanarayanan.kuppuswamy@...ux.intel.com
Cc:     Pali Rohár <pali.rohar@...il.com>,
        Mario Limonciello <mario.limonciello@...l.com>,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        "Edward O'Callaghan" <quasisec@...gle.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] dell-smbios: fix string overflow

On Wed, Nov 8, 2017 at 7:22 PM, sathyanarayanan kuppuswamy
<sathyanarayanan.kuppuswamy@...ux.intel.com> wrote:
> Hi,
>
> I recommend using "platform/x86: dell-smbios:" in commit header.

Ok, noted. I usually try to follow the lines for each maintainer, but
I'm not always
keeping track of each one, sorry.

> On 11/08/2017 04:08 AM, 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
>
> Don't need to include the error log in commit message. Just explaining the
> issue is good enough.

I always include the messages I get, it helps a lot when you run into a related
problem and find it in either the git log or using google search.

It's particularly useful when patches that introduce warnings get backported
to stable kernels.

      Arnd