Re: [PATCH 02/11] scsi: devinfo: rework scsi_strcpy_devinfo()

From: "Arnd Bergmann" <arnd@arndb.de>
To: "Justin Stitt" <justinstitt@google.com>,
	"Arnd Bergmann" <arnd@kernel.org>
Cc: linux-kernel@vger.kernel.org,
	"James E.J. Bottomley" <jejb@linux.ibm.com>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	"Chris Down" <chris@chrisdown.name>,
	"Petr Mladek" <pmladek@suse.com>,
	"Bart Van Assche" <bvanassche@acm.org>,
	linux-scsi@vger.kernel.org
Subject: Re: [PATCH 02/11] scsi: devinfo: rework scsi_strcpy_devinfo()
Date: Fri, 29 Mar 2024 00:18:06 +0100	[thread overview]
Message-ID: <ba922b28-e906-4d9a-90c7-8505d60f611d@app.fastmail.com> (raw)
In-Reply-To: <opeccmuhptoldyr2xfwstb4uwwgfiupk3kmjkxvke2itq6cuyn@jcx4v3a5ww2f>

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@arndb.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