linux-kernel - RE: [PATCH v3 0/4] Make sscanf() stricter

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <23df90dd35874fd89c64906e6a6de164@AcuMS.aculab.com>
Date:   Wed, 14 Jun 2023 08:23:56 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Demi Marie Obenour' <demi@...isiblethingslab.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
CC:     Alexey Dobriyan <adobriyan@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        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>
Subject: RE: [PATCH v3 0/4] Make sscanf() stricter

From: Demi Marie Obenour
> Sent: 13 June 2023 16:35
> 
> On Tue, Jun 13, 2023 at 01:02:59PM +0000, David Laight wrote:
> > From: Demi Marie Obenour
> > > Sent: 12 June 2023 22:23
> > ....
> > > sscanf(), except to the extent that -Werror=format can keep working.
> > > Userspace sscanf() is almost useless: it has undefined behavior on
> > > integer overflow and swallows spaces that should usually be rejected.
> >
> > scanf() is designed for parsing space separated data.
> > Eating spaces it part of its job description.
> >
> > 	David
> 
> In this case I would prefer to have two versions: one that eats spaces
> and one that does not.  For instance, I don’t think any user of
> xenbus_scanf() wants the space-swallowing behavior.  This can be worked
> around in xenbus_scanf(), of course, by having it reject strings with
> spaces (as determened by isspace()) before calling vsscanf().

What sort of formats and data are being used?
The "%s" format terminates on whitespace.
Even stroul() (and friends) will skip leading whitespace.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)