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From: "Tobin C. Harding" <me@tobin.cc>
To: Joe Perches <joe@perches.com>
Cc: kernel-hardening@lists.openwall.com,
	"Jason A. Donenfeld" <Jason@zx2c4.com>,
	Theodore Ts'o <tytso@mit.edu>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Kees Cook <keescook@chromium.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Tycho Andersen <tycho@docker.com>,
	"Roberts, William C" <william.c.roberts@intel.com>,
	Tejun Heo <tj@kernel.org>,
	Jordan Glover <Golden_Miller83@protonmail.ch>,
	Greg KH <gregkh@linuxfoundation.org>,
	Petr Mladek <pmladek@suse.com>, Ian Campbell <ijc@hellion.org.uk>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <wilal.deacon@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Chris Fries <cfries@google.com>,
	Dave Weinstein <olorin@google.com>,
	Daniel Micay <danielmicay@gmail.com>,
	Djalal Harouni <tixxdz@gmail.com>,
	linux-kernel@vger.kernel.org
Subject: [kernel-hardening] Re: [PATCH V8 1/2] printk: remove tabular output for NULL pointer
Date: Thu, 26 Oct 2017 17:27:34 +1100	[thread overview]
Message-ID: <20171026062734.GH12341@eros> (raw)
In-Reply-To: <1508993843.10651.22.camel@perches.com>

Hi Joe,

thanks for your review.

On Wed, Oct 25, 2017 at 09:57:23PM -0700, Joe Perches wrote:
> On Thu, 2017-10-26 at 13:53 +1100, Tobin C. Harding wrote:
> > Currently pointer() checks for a NULL pointer argument and then if so
> > attempts to print "(null)" with _some_ standard width. This width cannot
> > correctly be ascertained here because many of the printk specifiers
> > print pointers of varying widths.
> 
> I believe this is not a good change.
> Only pointers without a <foo> extension call pointer()

Sorry, I don't understand what you mean here. All the %p<foo> specifier code is
handled by pointer()?

> > Remove the attempt to print NULL pointers with a correct width.
> 
> the correct width for a %p is the default width.

It is the default width if we are printing addresses. Once we hash 64
bit address to a 32 bit identifier then we don't have a default width.

> The correct width for %p<foo> is unknown.

I agree.

If I have misunderstood you, please forgive me. I am very appreciative
of the reviews this patch is getting and the patience the list is having
with the many iterations.

thanks,
Tobin.

WARNING: multiple messages have this Message-ID (diff)
From: "Tobin C. Harding" <me@tobin.cc>
To: Joe Perches <joe@perches.com>
Cc: kernel-hardening@lists.openwall.com,
	"Jason A. Donenfeld" <Jason@zx2c4.com>,
	"Theodore Ts'o" <tytso@mit.edu>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Kees Cook <keescook@chromium.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Tycho Andersen <tycho@docker.com>,
	"Roberts, William C" <william.c.roberts@intel.com>,
	Tejun Heo <tj@kernel.org>,
	Jordan Glover <Golden_Miller83@protonmail.ch>,
	Greg KH <gregkh@linuxfoundation.org>,
	Petr Mladek <pmladek@suse.com>, Ian Campbell <ijc@hellion.org.uk>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <wilal.deacon@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Chris Fries <cfries@google.com>,
	Dave Weinstein <olorin@google.com>,
	Daniel Micay <danielmicay@gmail.com>,
	Djalal Harouni <tixxdz@gmail.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH V8 1/2] printk: remove tabular output for NULL pointer
Date: Thu, 26 Oct 2017 17:27:34 +1100	[thread overview]
Message-ID: <20171026062734.GH12341@eros> (raw)
In-Reply-To: <1508993843.10651.22.camel@perches.com>

Hi Joe,

thanks for your review.

On Wed, Oct 25, 2017 at 09:57:23PM -0700, Joe Perches wrote:
> On Thu, 2017-10-26 at 13:53 +1100, Tobin C. Harding wrote:
> > Currently pointer() checks for a NULL pointer argument and then if so
> > attempts to print "(null)" with _some_ standard width. This width cannot
> > correctly be ascertained here because many of the printk specifiers
> > print pointers of varying widths.
> 
> I believe this is not a good change.
> Only pointers without a <foo> extension call pointer()

Sorry, I don't understand what you mean here. All the %p<foo> specifier code is
handled by pointer()?

> > Remove the attempt to print NULL pointers with a correct width.
> 
> the correct width for a %p is the default width.

It is the default width if we are printing addresses. Once we hash 64
bit address to a 32 bit identifier then we don't have a default width.

> The correct width for %p<foo> is unknown.

I agree.

If I have misunderstood you, please forgive me. I am very appreciative
of the reviews this patch is getting and the patience the list is having
with the many iterations.

thanks,
Tobin.

  reply	other threads:[~2017-10-26  6:27 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-26  2:53 [kernel-hardening] [PATCH V8 0/2] printk: hash addresses printed with %p Tobin C. Harding
2017-10-26  2:53 ` Tobin C. Harding
2017-10-26  2:53 ` [kernel-hardening] [PATCH V8 1/2] printk: remove tabular output for NULL pointer Tobin C. Harding
2017-10-26  2:53   ` Tobin C. Harding
2017-10-26  4:57   ` [kernel-hardening] " Joe Perches
2017-10-26  4:57     ` Joe Perches
2017-10-26  6:27     ` Tobin C. Harding [this message]
2017-10-26  6:27       ` Tobin C. Harding
2017-10-26  8:05       ` [kernel-hardening] " Joe Perches
2017-10-26  8:05         ` Joe Perches
2017-10-26  9:37         ` [kernel-hardening] " Tobin C. Harding
2017-10-26  9:37           ` Tobin C. Harding
2017-10-26 14:47           ` [kernel-hardening] " Joe Perches
2017-10-26 14:47             ` Joe Perches
2017-10-26 23:57             ` [kernel-hardening] " Tobin C. Harding
2017-10-26 23:57               ` Tobin C. Harding
2017-10-27  0:11               ` [kernel-hardening] " Joe Perches
2017-10-27  0:11                 ` Joe Perches
2017-10-26  2:53 ` [kernel-hardening] [PATCH V8 2/2] printk: hash addresses printed with %p Tobin C. Harding
2017-10-26  2:53   ` Tobin C. Harding
2017-10-26  2:58   ` [kernel-hardening] " Tobin C. Harding
2017-10-26  2:58     ` Tobin C. Harding
2017-10-30 21:33     ` [kernel-hardening] " Steven Rostedt
2017-10-30 21:33       ` Steven Rostedt
2017-10-30 22:41       ` [kernel-hardening] " Tobin C. Harding
2017-10-30 22:41         ` Tobin C. Harding
2017-10-31  0:00         ` [kernel-hardening] " Steven Rostedt
2017-10-31  0:00           ` Steven Rostedt
2017-10-31  2:00           ` [kernel-hardening] " Tobin C. Harding
2017-10-31  2:00             ` Tobin C. Harding
2017-10-26  3:11   ` [kernel-hardening] " Jason A. Donenfeld
2017-10-26  3:11     ` Jason A. Donenfeld
2017-10-27 13:33 ` [kernel-hardening] Re: [PATCH V8 0/2] " Sergey Senozhatsky
2017-10-27 13:33   ` Sergey Senozhatsky
2017-10-31 23:35   ` [kernel-hardening] " Tobin C. Harding
2017-10-31 23:35     ` Tobin C. Harding
2017-11-02  8:23     ` [kernel-hardening] " Sergey Senozhatsky
2017-11-02  8:23       ` Sergey Senozhatsky
2017-11-02 10:14       ` [kernel-hardening] " Tobin C. Harding
2017-11-02 10:14         ` Tobin C. Harding
2017-11-02 13:43         ` [kernel-hardening] " Roberts, William C
2017-11-02 13:43           ` Roberts, William C
2017-11-02 16:04         ` [kernel-hardening] " Sergey Senozhatsky
2017-11-02 16:04           ` Sergey Senozhatsky
2017-11-02 18:11           ` [kernel-hardening] " Petr Nejedlý
2017-10-30 22:03 ` Kees Cook
2017-10-30 22:03   ` Kees Cook
2017-10-30 22:33   ` [kernel-hardening] " Tobin C. Harding
2017-10-30 22:33     ` Tobin C. Harding
2017-10-31  2:08     ` [kernel-hardening] " Joe Perches
2017-10-31  2:08       ` Joe Perches
2017-10-31 23:16       ` [kernel-hardening] " Tobin C. Harding
2017-10-31 23:16         ` Tobin C. Harding
2017-10-31 23:33         ` [kernel-hardening] " Joe Perches
2017-10-31 23:33           ` Joe Perches
2017-11-03  5:13           ` [kernel-hardening] " Vinod Koul
2017-11-03  5:13             ` Vinod Koul

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