linux-hardening - Re: [PATCH v4] checkpatch: add check for snprintf to scnprintf

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Date: Thu, 11 Apr 2024 15:10:57 -0700
From: Justin Stitt <justinstitt@...gle.com>
To: Joe Perches <joe@...ches.com>
Cc: Christophe JAILLET <christophe.jaillet@...adoo.fr>, Andy Whitcroft <apw@...onical.com>, 
	Dwaipayan Ray <dwaipayanray1@...il.com>, Lukas Bulwahn <lukas.bulwahn@...il.com>, 
	linux-kernel@...r.kernel.org, Lee Jones <lee@...nel.org>, 
	linux-hardening@...r.kernel.org, Kees Cook <keescook@...omium.org>, 
	Finn Thain <fthain@...ux-m68k.org>
Subject: Re: [PATCH v4] checkpatch: add check for snprintf to scnprintf

On Thu, Apr 11, 2024 at 1:56 PM Joe Perches <joe@...ches.com> wrote:
> It could.
>
> # {v}snprintf uses that should likely be {v}scnprintf
>                 if ($line =~ /\b((v?)snprintf)\s*\(/) {
>                         WARN("SNPRINTF",
>                              "Prefer ${2}scnprintf over $1 - see: https://github.com/KSPP/linux/issues/105\n" . $herecurr);
>                 }
>
>
>
> Though I also think it's better to use lore rather than github

I am fine with making the UX change in v5 regarding using ${2} and $1
but I wish someone could have said something about the Github links
earlier, we already have a pattern going with these string api
changes:

     "Prefer strscpy over strcpy - see:
https://github.com/KSPP/linux/issues/88\n" . $herecurr);
}

...
# strlcpy uses that should likely be strscpy
if ($line =~ /\bstrlcpy\s*\(/) {
WARN("STRLCPY",
     "Prefer strscpy over strlcpy - see:
https://github.com/KSPP/linux/issues/89\n" . $herecurr);
}

# strncpy uses that should likely be strscpy or strscpy_pad
if ($line =~ /\bstrncpy\s*\(/) {
WARN("STRNCPY",
     "Prefer strscpy, strscpy_pad, or __nonstring over strncpy - see:
https://github.com/KSPP/linux/issues/90\n" . $herecurr);
}

# {v}snprintf uses that should likely be {v}scnprintf
if ($line =~ /\b(v|)snprintf\s*\(/) {
WARN("SNPRINTF",
     "Prefer ${2}scnprintf over $1 - see:
https://github.com/KSPP/linux/issues/105\n" . $herecurr);
...


It should be noted that nowhere else is a lore link or github link
provided during a warning, so there really is no precedence. Joe what
should we do?

>