linux-kernel - Re: [PATCH AUTOSEL 4.18 39/65] fs/cifs: suppress a string overflow warning

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Message-ID: <20181001234841.GF69414@sasha-vm>
Date:   Mon, 1 Oct 2018 23:48:43 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     Stephen Rothwell <sfr@...b.auug.org.au>
CC:     "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Steven French <Steven.French@...rosoft.com>
Subject: Re: [PATCH AUTOSEL 4.18 39/65] fs/cifs: suppress a string overflow
 warning

On Mon, Oct 01, 2018 at 11:22:46AM +1000, Stephen Rothwell wrote:
>Hi Sasha,
>
>On Mon, 1 Oct 2018 00:38:27 +0000 Sasha Levin <Alexander.Levin@...rosoft.com> wrote:
>>
>> From: Stephen Rothwell <sfr@...b.auug.org.au>
>>
>> [ Upstream commit bcfb84a996f6fa90b5e6e2954b2accb7a4711097 ]
>>
>> A powerpc build of cifs with gcc v8.2.0 produces this warning:
>>
>> fs/cifs/cifssmb.c: In function ‘CIFSSMBNegotiate’:
>> fs/cifs/cifssmb.c:605:3: warning: ‘strncpy’ writing 16 bytes into a region of size 1 overflows the destination [-Wstringop-overflow=]
>>    strncpy(pSMB->DialectsArray+count, protocols[i].name, 16);
>>    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>
>> Since we are already doing a strlen() on the source, change the strncpy
>> to a memcpy().
>>
>> Signed-off-by: Stephen Rothwell <sfr@...b.auug.org.au>
>> Signed-off-by: Steve French <stfrench@...rosoft.com>
>> Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
>
>Just wondering if this should be included as it only fixes a build
>warning, there is no actual bug.  Same for the 4.9 and 4.14 versions.

Hi Stephen,

We try to follow the same no-warnings policy like upstream and take
warning fixes into stable tree. It makes it possible to catch
"real" warnings in stable kernel that resulted from backporting issues.

--
Thanks,
Sasha