linux-hardening - Re: [PATCH] scsi: bnx2fc: replace deprecated strncpy with strscpy

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Message-ID: <202310241728.6CEDB92754@keescook>
Date: Tue, 24 Oct 2023 17:28:32 -0700
From: Kees Cook <keescook@...omium.org>
To: Justin Stitt <justinstitt@...gle.com>
Cc: Saurav Kashyap <skashyap@...vell.com>, Javed Hasan <jhasan@...vell.com>,
	GR-QLogic-Storage-Upstream@...vell.com,
	"James E.J. Bottomley" <jejb@...ux.ibm.com>,
	"Martin K. Petersen" <martin.petersen@...cle.com>,
	linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-hardening@...r.kernel.org
Subject: Re: [PATCH] scsi: bnx2fc: replace deprecated strncpy with strscpy

On Mon, Oct 23, 2023 at 08:12:22PM +0000, Justin Stitt wrote:
> strncpy() is deprecated for use on NUL-terminated destination strings
> [1] and as such we should prefer more robust and less ambiguous string
> interfaces.
> 
> We expect hba->chip_num to be NUL-terminated based on its usage with
> format strings:
> 
> 	snprintf(fc_host_symbolic_name(lport->host), 256,
> 		 "%s (QLogic %s) v%s over %s",
> 		BNX2FC_NAME, hba->chip_num, BNX2FC_VERSION,
> 		interface->netdev->name);
> 
> Moreover, NUL-padding is not required as hba is zero-allocated from its
> callsite:
> 
> 	hba = kzalloc(sizeof(*hba), GFP_KERNEL);
> 
> Considering the above, a suitable replacement is `strscpy` [2] due to
> the fact that it guarantees NUL-termination on the destination buffer
> without unnecessarily NUL-padding.
> 
> Regarding stats_addr->version, I've opted to also use strscpy() instead
> of strscpy_pad() as I typically see these XYZ_get_strings() pass
> zero-allocated data. I couldn't track all of where
> bnx2fc_ulp_get_stats() is used and if required, we could opt for
> strscpy_pad().
> 
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
> Link: https://github.com/KSPP/linux/issues/90
> Cc: linux-hardening@...r.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@...gle.com>

This all looks correct to me.

Reviewed-by: Kees Cook <keescook@...omium.org>

-- 
Kees Cook