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Message-ID: <96b45245-bdd8-119d-e7a9-44eb36be0f97@rasmusvillemoes.dk>
Date: Mon, 12 Jun 2023 12:53:06 +0200
From: Rasmus Villemoes <linux@...musvillemoes.dk>
To: Demi Marie Obenour <demi@...isiblethingslab.com>,
Hans de Goede <hdegoede@...hat.com>,
Mauro Carvalho Chehab <mchehab@...nel.org>,
Sakari Ailus <sakari.ailus@...ux.intel.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Juergen Gross <jgross@...e.com>,
Stefano Stabellini <sstabellini@...nel.org>,
Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>,
Lee Jones <lee@...nel.org>, Andy Lutomirski <luto@...nel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Vincenzo Frascino <vincenzo.frascino@....com>,
Petr Mladek <pmladek@...e.com>,
Steven Rostedt <rostedt@...dmis.org>,
Sergey Senozhatsky <senozhatsky@...omium.org>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: linux-media@...r.kernel.org, linux-staging@...ts.linux.dev,
linux-kernel@...r.kernel.org, xen-devel@...ts.xenproject.org,
Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH v3 2/4] vsscanf(): Integer overflow is a conversion
failure
On 10/06/2023 22.40, Demi Marie Obenour wrote:
> sscanf() and friends currently ignore integer overflow, but this is a
> bad idea. It is much better to detect integer overflow errors and
> consider this a conversion failure.
Perhaps. And maybe I even agree. But not like this:
> while (*fmt) {
> /* skip any white space in format */
> @@ -3464,6 +3474,9 @@ int vsscanf(const char *buf, const char *fmt, va_list args)
> break;
> ++fmt;
>
> + allow_overflow = *fmt == '!';
> + fmt += (int)allow_overflow;
> +
You can't do that. Or, at least, you won't be able to actually use %!d
anywhere, because the compiler will yell at you:
lib/vsprintf.c: In function ‘foobar’:
lib/vsprintf.c:3727:26: error: unknown conversion type character ‘!’ in
format [-Werror=format=]
3727 | ret = sscanf("12345", "%!d", &val);
| ^
So NAK.
Also, when you make significant changes to the sscanf implementation,
I'd expect the diffstat for the patch series to contain lib/test_scanf.c.
Rasmus
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