From: Linus Torvalds <torvalds@linux-foundation.org>
To: Petr Mladek <pmladek@suse.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
"Tobin C . Harding" <me@tobin.cc>, Joe Perches <joe@perches.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@suse.cz>
Subject: Re: [PATCH] vsprintf: Make "null" pointer dereference more robust
Date: Fri, 9 Mar 2018 11:05:17 -0800 [thread overview]
Message-ID: <CA+55aFwT-Vd+sVdAVemUjUvkNYFiLyVMHZxv9hF6KzRM7i4Yrg@mail.gmail.com> (raw)
In-Reply-To: <20180309150153.3sxbbpd6jdn2d5yy@pathway.suse.cz>
On Fri, Mar 9, 2018 at 7:01 AM, Petr Mladek <pmladek@suse.com> wrote:
> Also it makes the handling unified. We print:
>
> + (null) when pure NULL pointer is dereferenced
> + (efault) when an invalid address is dereferenced
> + pointer address otherwise
This is still fundamentally completely wrong.
It never prints "pointer address", and if it were to do that, it would be wrong.
It should never ever trigger for an address operation, only for the
"we will get _data_ from the ponter".
The strchr thing is also completely broken, and in a very subtle way.
"strchr(string, 0)" is special, and the Open Group states
"The terminating null byte is considered to be part of the string"
so a NUL character will *always* return success, which is actually
completely wrong for this case, because now it does that whole crazy
<efault> thing for %p that it shouldn't do.
Not that I actually verified that our strchr() follows the actual
rules anyway - I personally consider "strchr(string, 0)" to not really
be "special", but be a bug. Either way, the comment is wrong, but the
code is also wrong.
Linus
next prev parent reply other threads:[~2018-03-09 19:05 UTC|newest]
Thread overview: 87+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-16 21:07 [PATCH v2 1/9] lib/test_printf: Mark big constant with ULL Andy Shevchenko
2018-02-16 21:07 ` [PATCH v2 2/9] lib/vsprintf: Make dec_spec global Andy Shevchenko
2018-04-11 9:44 ` Petr Mladek
2018-02-16 21:07 ` [PATCH v2 3/9] lib/vsprintf: Make strspec global Andy Shevchenko
2018-04-11 9:44 ` Petr Mladek
2018-02-16 21:07 ` [PATCH v2 4/9] lib/vsprintf: Make flag_spec global Andy Shevchenko
2018-04-11 9:45 ` Petr Mladek
2018-02-16 21:07 ` [PATCH v2 5/9] lib/vsprintf: Move pointer_string() upper Andy Shevchenko
2018-04-11 9:45 ` Petr Mladek
2018-02-16 21:07 ` [PATCH v2 6/9] lib/vsprintf: Deduplicate pointer_string() Andy Shevchenko
2018-04-11 9:46 ` Petr Mladek
2018-02-16 21:07 ` [PATCH v2 7/9] lib/vsprintf: Replace space with '_' before crng is ready Andy Shevchenko
2018-02-20 2:57 ` [此邮件可能存在风险] " Yang, Shunyong
2018-04-11 9:47 ` Petr Mladek
2018-02-16 21:07 ` [PATCH v2 8/9] lib/vsprintf: Remove useless NULL checks Andy Shevchenko
2018-02-27 15:50 ` Petr Mladek
2018-02-27 17:35 ` Andy Shevchenko
2018-02-28 10:04 ` Petr Mladek
2018-02-28 10:42 ` Andy Shevchenko
2018-03-02 12:51 ` Petr Mladek
2018-03-02 12:53 ` [PATCH] vsprintf: Make "null" pointer dereference more robust Petr Mladek
2018-03-02 14:17 ` Andy Shevchenko
2018-03-05 14:53 ` Petr Mladek
2018-03-29 15:13 ` Petr Mladek
2018-03-29 16:11 ` Joe Perches
2018-03-05 15:16 ` Rasmus Villemoes
2018-03-05 15:25 ` Andy Shevchenko
2018-03-06 9:25 ` Petr Mladek
2018-03-06 9:56 ` Andy Shevchenko
2018-03-07 15:52 ` Petr Mladek
2018-03-07 18:18 ` Andy Shevchenko
2018-03-07 18:34 ` Linus Torvalds
2018-03-08 14:18 ` Petr Mladek
2018-03-08 16:45 ` Linus Torvalds
2018-03-08 17:26 ` Linus Torvalds
2018-03-09 15:01 ` Petr Mladek
2018-03-09 19:05 ` Linus Torvalds [this message]
2018-03-14 14:09 ` [PATCH v3] vsprintf: Prevent crash when dereferencing invalid pointers Petr Mladek
2018-03-14 22:12 ` Rasmus Villemoes
2018-03-15 15:07 ` Petr Mladek
2018-03-15 17:07 ` Steven Rostedt
2018-03-15 17:06 ` Steven Rostedt
2018-03-15 0:57 ` Sergey Senozhatsky
2018-03-15 7:58 ` Sergey Senozhatsky
2018-03-15 8:03 ` Sergey Senozhatsky
2018-03-15 17:01 ` Steven Rostedt
2018-03-16 1:18 ` Sergey Senozhatsky
2018-03-16 1:35 ` Linus Torvalds
2018-03-16 5:53 ` Sergey Senozhatsky
2018-03-16 8:55 ` Petr Mladek
2018-03-16 14:32 ` Steven Rostedt
2018-03-17 1:29 ` Sergey Senozhatsky
2018-03-15 13:07 ` Andy Shevchenko
2018-03-15 13:09 ` Andy Shevchenko
2018-03-15 15:26 ` Petr Mladek
2018-03-16 18:19 ` Andy Shevchenko
2018-03-29 14:53 ` Petr Mladek
2018-04-02 14:15 ` Andy Shevchenko
2018-04-03 1:12 ` Sergey Senozhatsky
2018-04-03 11:52 ` Petr Mladek
2018-04-03 11:56 ` Andy Shevchenko
2018-04-03 13:57 ` Sergey Senozhatsky
2018-04-03 11:46 ` Petr Mladek
2018-04-03 11:54 ` Andy Shevchenko
2018-04-03 13:13 ` Petr Mladek
2018-04-03 13:40 ` Andy Shevchenko
2018-04-03 14:50 ` Petr Mladek
2018-03-15 14:48 ` kbuild test robot
2018-03-15 20:26 ` kbuild test robot
2018-03-06 18:11 ` [PATCH 1/2] vsprintf: distinguish between (null), (err) and (invalid) pointer derefs Adam Borowski
2018-03-06 18:11 ` [PATCH 2/2] vsprintf: don't dereference pointers to the first or last page Adam Borowski
2018-03-07 13:22 ` Andy Shevchenko
2018-03-07 13:17 ` [PATCH 1/2] vsprintf: distinguish between (null), (err) and (invalid) pointer derefs Andy Shevchenko
2018-03-07 13:42 ` Adam Borowski
2018-03-07 13:29 ` Andy Shevchenko
2018-03-02 14:15 ` [PATCH v2 8/9] lib/vsprintf: Remove useless NULL checks Andy Shevchenko
2018-03-05 14:57 ` Petr Mladek
2018-02-28 10:44 ` Andy Shevchenko
2018-03-01 14:56 ` Andy Shevchenko
2018-02-16 21:07 ` [PATCH v2 9/9] lib/vsprintf: Mark expected switch fall-through Andy Shevchenko
2018-04-11 9:47 ` Petr Mladek
2018-02-18 12:58 ` [PATCH v2 1/9] lib/test_printf: Mark big constant with ULL Luc Van Oostenryck
2018-02-18 14:20 ` Andy Shevchenko
2018-02-19 15:24 ` Andy Shevchenko
2018-04-11 9:41 ` Petr Mladek
2018-02-18 21:52 ` Tobin C. Harding
2018-02-18 23:55 ` Andy Shevchenko
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