linux-kernel - Re: [PATCH v6 8/9] vsprintf: Prevent crash when dereferencing invalid pointers

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Message-ID: <20190219134956.GM9224@smile.fi.intel.com>
Date:   Tue, 19 Feb 2019 15:49:56 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Petr Mladek <pmladek@...e.com>,
        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>,
        Steven Rostedt <rostedt@...dmis.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6 8/9] vsprintf: Prevent crash when dereferencing
 invalid pointers

On Tue, Feb 19, 2019 at 09:51:15PM +0900, Sergey Senozhatsky wrote:
> On (02/19/19 13:02), Andy Shevchenko wrote:
> [..]
> > And if it's not? You will get in either case incomplete information,
> > but at least with "(e" (or even "(") you might get a clue that it
> > errornous conditions.
> 
> The thing I'm signaling here is that in some cases we still can
> crash the kernel; with the difference that invalid dereference
> can now be a memory corruption. Just saying.

Wouldn't that mean that the culprit in the caller, not in the callee?

(As far as I got your another example with badly called sprintf() which may
 overwrite stack, etc).

-- 
With Best Regards,
Andy Shevchenko