From: Petr Mladek <pmladek@suse.com>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
"Tobin C . Harding" <me@tobin.cc>, Joe Perches <joe@perches.com>,
Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@suse.cz>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 4/9] vsprintf: Consolidate handling of unknown pointer specifiers
Date: Mon, 9 Apr 2018 15:50:28 +0200 [thread overview]
Message-ID: <20180409135028.ymyvsqxup7zm5vgc@pathway.suse.cz> (raw)
In-Reply-To: <1523111200.21176.416.camel@linux.intel.com>
On Sat 2018-04-07 17:26:40, Andy Shevchenko wrote:
> On Wed, 2018-04-04 at 10:58 +0200, Petr Mladek wrote:
> > There are few printk formats that make sense only with two or more
> > specifiers. Also some specifiers make sense only when a kernel feature
> > is enabled.
> >
> > The handling of unknown specifiers is strange, inconsistent, and
> > even leaking the address. For example, netdev_bits() prints the
> > non-hashed pointer value or clock() prints "(null)".
> >
> > The best solution seems to be in flags_string(). It does not print any
> > misleading value. Instead it calls WARN_ONCE() describing the unknown
> > specifier. Therefore it clearly shows the problem and helps to find
> > it.
> >
> > Note that WARN_ONCE() used to cause recursive printk(). But it is safe
> > now because vscnprintf() is called in printk_safe context from
> > vprintk_emit().
> >
>
> > - if (!IS_ENABLED(CONFIG_HAVE_CLK) || !clk)
> > + if (!IS_ENABLED(CONFIG_HAVE_CLK)) {
> > + WARN_ONCE(1, "Unsupported pointer format specifier:
> > %%pC\n");
> > + return buf;
> > + }
> > +
> > + if (!clk)
> > return string(buf, end, NULL, spec);
>
> This change collides with my patch series. Can you elaborate what your
> thoughts are about my patches? Are you going incorporate them to your
> series? Should I send them independently?
Good question. I think that the best solution will be that I go
over your patchset and just add all valid ones into printk.git
for-4.18. Then I will base v5 of this patchset on top of it.
I should have done this earlier. But I did not expect that long
way for the access-check stuff. We originally planned to
do the access check first, see
https://lkml.kernel.org/r/1520000254.10722.389.camel@linux.intel.com
But the access check patchset still need some love, so it makes
sense to switch the order.
Best Regards,
Petr
next prev parent reply other threads:[~2018-04-09 13:50 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-04 8:58 [PATCH v4 0/9] vsprintf: Prevent silent crashes and consolidate error handling Petr Mladek
2018-04-04 8:58 ` [PATCH v4 1/9] vsprintf: Shuffle ptr_to_id() code Petr Mladek
2018-04-04 8:58 ` [PATCH v4 2/9] vsprintf: Consistent %pK handling for kptr_restrict == 0 Petr Mladek
2018-04-04 23:10 ` Sergey Senozhatsky
2018-04-05 14:34 ` Petr Mladek
2018-04-05 13:04 ` Andy Shevchenko
2018-04-05 14:46 ` Petr Mladek
2018-04-07 14:08 ` Andy Shevchenko
2018-04-09 12:05 ` Petr Mladek
2018-04-09 12:11 ` Andy Shevchenko
2018-04-04 8:58 ` [PATCH v4 3/9] vsprintf: Do not check address of well-known strings Petr Mladek
2018-04-05 13:30 ` Rasmus Villemoes
2018-04-06 9:15 ` Petr Mladek
2018-04-07 14:12 ` Andy Shevchenko
2018-04-09 12:19 ` Petr Mladek
2018-04-10 10:05 ` Andy Shevchenko
2018-04-04 8:58 ` [PATCH v4 4/9] vsprintf: Consolidate handling of unknown pointer specifiers Petr Mladek
2018-04-05 14:25 ` Rasmus Villemoes
2018-04-05 23:45 ` Joe Perches
2018-04-05 23:55 ` Joe Perches
2018-04-06 11:43 ` Petr Mladek
2018-04-06 13:17 ` Rasmus Villemoes
2018-04-06 14:27 ` Joe Perches
2018-04-09 12:30 ` Petr Mladek
2018-04-07 14:23 ` Andy Shevchenko
2018-04-06 23:52 ` Sergey Senozhatsky
2018-04-06 23:59 ` Joe Perches
2018-04-07 0:33 ` Sergey Senozhatsky
2018-04-07 1:00 ` Joe Perches
2018-04-07 1:17 ` Sergey Senozhatsky
2018-04-06 11:25 ` Petr Mladek
2018-04-07 14:26 ` Andy Shevchenko
2018-04-09 13:50 ` Petr Mladek [this message]
2018-04-10 11:41 ` Andy Shevchenko
2018-04-11 9:52 ` Petr Mladek
2018-04-24 16:47 ` Andy Shevchenko
2018-04-04 8:58 ` [PATCH v4 5/9] vsprintf: Factor out %p[iI] handler as ip_addr_string() Petr Mladek
2018-04-04 23:58 ` Sergey Senozhatsky
2018-04-05 14:14 ` Petr Mladek
2018-04-07 14:30 ` Andy Shevchenko
2018-04-04 8:58 ` [PATCH v4 6/9] vsprintf: Factor out %pV handler as va_format() Petr Mladek
2018-04-04 14:26 ` Joe Perches
2018-04-06 13:12 ` Petr Mladek
2018-04-06 14:19 ` Joe Perches
2018-04-09 11:44 ` Petr Mladek
2018-04-09 11:59 ` Joe Perches
2018-04-04 8:58 ` [PATCH v4 7/9] vsprintf: Factor out %pO handler as kobject_string() Petr Mladek
2018-04-04 23:35 ` Sergey Senozhatsky
2018-04-04 23:43 ` Sergey Senozhatsky
2018-04-05 14:02 ` Petr Mladek
2018-04-04 8:58 ` [PATCH v4 8/9] vsprintf: Prevent crash when dereferencing invalid pointers Petr Mladek
2018-04-05 14:46 ` Rasmus Villemoes
2018-04-06 12:26 ` Petr Mladek
2018-04-06 13:12 ` Rasmus Villemoes
2018-04-10 13:26 ` Petr Mladek
2018-04-06 9:37 ` Rasmus Villemoes
2018-04-04 8:58 ` [PATCH v4 9/9] vsprintf: Avoid confusion between invalid address and value Petr Mladek
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