linux-kernel - Re: [PATCH v4 3/9] vsprintf: Do not check address of well-known strings

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]

Date:   Tue, 10 Apr 2018 13:05:22 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Rasmus Villemoes <linux@...musvillemoes.dk>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        "Tobin C . Harding" <me@...in.cc>, Joe Perches <joe@...ches.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.cz>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 3/9] vsprintf: Do not check address of well-known
 strings

On Mon, 2018-04-09 at 14:19 +0200, Petr Mladek wrote:
> On Sat 2018-04-07 17:12:35, Andy Shevchenko wrote:
> > On Fri, 2018-04-06 at 11:15 +0200, Petr Mladek wrote:
> > > On Thu 2018-04-05 15:30:51, Rasmus Villemoes wrote:
> > > > On 2018-04-04 10:58, Petr Mladek wrote:

> > > > > 
> > > > Please leave string() alone, except for moving the < PAGE_SIZE
> > > > check
> > > > to
> > > > a new helper checked_string (feel free to find a better name),
> > > > and
> > > > use
> > > > checked_string for handling %s and possibly the few other cases
> > > > where
> > > > we're passing a user-supplied pointer. That avoids cluttering
> > > > the
> > > > entire
> > > > file with double-underscore calls, and e.g. in the %pO case,
> > > > it's
> > > > easier
> > > > to understand why one uses two different *string() helpers if
> > > > the
> > > > name
> > > > of one somehow conveys how it is different from the other.
> > > 
> > > I understand your reasoning. I thought about exactly this as well.
> > > My problem is that string() will then be unsafe. It might be
> > > dangerous
> > > when porting patches.
> > 
> > I agree with Rasmus, and your argument here from my point of view
> > kinda
> > weak. Are we really going to backport this patches? Why? We lived
> > w/o
> > them for a long time. What's changed now?
> 
> Someone might have out-of-tree patch that adds yet another format
> specifier. It might call string() that checks for (null) now but
> it it won't if we rename it as you suggest. People used to safe
> string() might miss this when the patch is send upstream for
> inclusion, ...

This is even weaker argument. Sorry, but I don't care about out-of-tree
core patches. If they have them, they are doing completely wrong, or the
patches are crappy.

-- 
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Intel Finland Oy