linux-kernel - Re: [PATCH 02/11] scsi: devinfo: rework scsi_strcpy

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Message-Id: <ba922b28-e906-4d9a-90c7-8505d60f611d@app.fastmail.com>
Date: Fri, 29 Mar 2024 00:18:06 +0100
From: "Arnd Bergmann" <arnd@...db.de>
To: "Justin Stitt" <justinstitt@...gle.com>, "Arnd Bergmann" <arnd@...nel.org>
Cc: linux-kernel@...r.kernel.org, "James E.J. Bottomley" <jejb@...ux.ibm.com>,
 "Martin K. Petersen" <martin.petersen@...cle.com>,
 "Chris Down" <chris@...isdown.name>, "Petr Mladek" <pmladek@...e.com>,
 "Bart Van Assche" <bvanassche@....org>, linux-scsi@...r.kernel.org
Subject: Re: [PATCH 02/11] scsi: devinfo: rework scsi_strcpy_devinfo()

On Fri, Mar 29, 2024, at 00:14, Justin Stitt wrote:
>
> On Thu, Mar 28, 2024 at 03:04:46PM +0100, Arnd Bergmann wrote:
>> From: Arnd Bergmann <arnd@...db.de>
>> 
>> scsi_strcpy_devinfo() appears to work as intended but its semantics are
>> so confusing that gcc warns about it when -Wstringop-truncation is enabled:
>> 
>> In function 'scsi_strcpy_devinfo',
>>     inlined from 'scsi_dev_info_list_add_keyed' at drivers/scsi/scsi_devinfo.c:370:2:
>> drivers/scsi/scsi_devinfo.c:297:9: error: 'strncpy' specified bound 16 equals destination size [-Werror=stringop-truncation]
>>   297 |         strncpy(to, from, to_length);
>>       |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> 
>> Reorganize the function to completely separate the nul-terminated from
>> the space-padded/non-terminated case. The former is just strscpy_pad(),
>> while the latter does not have a standard function.
>>
>
> I did the same in a patch sent earlier (few weeks ago):
>
> https://lore.kernel.org/all/20240305-strncpy-drivers-scsi-mpi3mr-mpi3mr_fw-c-v3-5-5b78a13ff984@google.com/
>
> Maybe reviewers can chime in on which version is preferred and go from
> there.

I'm in favor of your version, it looks nicer and addresses the comment
that Bart had on mine.

     Arnd