From: Borislav Petkov <bp@alien8.de>
To: Robert Richter <rric@kernel.org>
Cc: Len Baker <len.baker@gmx.com>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Tony Luck <tony.luck@intel.com>,
James Morse <james.morse@arm.com>, Joe Perches <joe@perches.com>,
David Laight <David.Laight@aculab.com>,
Kees Cook <keescook@chromium.org>,
linux-hardening@vger.kernel.org, linux-edac@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] EDAC/mc: Prefer strscpy or scnprintf over strcpy, sprintf and snprintf
Date: Wed, 15 Sep 2021 13:58:25 +0200 [thread overview]
Message-ID: <YUHf4cEEKFjQznJS@zn.tnic> (raw)
In-Reply-To: <YT8S3poKyd5Nr5cK@rric.localdomain>
On Mon, Sep 13, 2021 at 10:59:10AM +0200, Robert Richter wrote:
> From 01a3c62a533e71984dfff7189e247b3e848f1449 Mon Sep 17 00:00:00 2001
> From: Len Baker <len.baker@gmx.com>
> Date: Fri, 3 Sep 2021 17:05:39 +0200
> Subject: [PATCH] EDAC/mc: Prefer strscpy or scnprintf over strcpy, sprintf
> and snprintf
>
> strcpy() performs no bounds checking on the destination buffer. This
> could result in linear overflows beyond the end of the buffer, leading
> to all kinds of misbehaviors. The safe replacement is strscpy().
> [1][2]
>
> However, to simplify and clarify the code, to concatenate labels use
> the scnprintf() function. This way it is not necessary to check the
> return value of strscpy (-E2BIG if the parameter count is 0 or the src
> was truncated) since the scnprintf returns always the number of chars
> written into the buffer. This function returns always a nul-terminated
> string even if it needs to be truncated.
>
> While at it, fix all other broken string generation code that wrongly
> interprets snprintf()'s return code or just uses sprintf(), implement
> that using scnprintf() here too. Drop breaks in loops around
> scnprintf() as it is safe now to loop. Moreover, the check is
> needless: For the case when the buffer is exhausted, len never gets
> zero because scnprintf() takes the full buffer length as input
> parameter, but excludes the trailing '\0' in its return code and thus,
> 1 is the minimum len.
>
> [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strcpy
> [2] https://github.com/KSPP/linux/issues/88
>
> [ rric: Replace snprintf() with scnprintf(), rework sprintf() user,
> drop breaks in loops around scnprintf(), introduce 'end' pointer to
> reduce pointer arithmetic, use prefix pattern for e->location,
> adjust subject and description ]
>
> Co-developed-by: Joe Perches <joe@perches.com>
> Signed-off-by: Joe Perches <joe@perches.com>
> Signed-off-by: Len Baker <len.baker@gmx.com>
> Signed-off-by: Robert Richter <rrichter@amd.com>
> ---
> drivers/edac/edac_mc.c | 42 ++++++++++++++++++------------------------
> 1 file changed, 18 insertions(+), 24 deletions(-)
Applied, thanks.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2021-09-15 11:58 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-03 15:05 [PATCH v6] EDAC/mc: Prefer strscpy or scnprintf over strcpy Len Baker
2021-09-03 17:03 ` Joe Perches
2021-09-04 11:23 ` Len Baker
2021-09-04 11:36 ` Borislav Petkov
2021-09-04 13:22 ` Len Baker
2021-09-13 8:59 ` [PATCH] EDAC/mc: Prefer strscpy or scnprintf over strcpy, sprintf and snprintf Robert Richter
2021-09-15 11:58 ` Borislav Petkov [this message]
2021-09-18 9:17 ` Len Baker
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