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From: Joe Perches <joe@perches.com>
To: "Tobin C. Harding" <me@tobin.cc>, kernel-hardening@lists.openwall.com
Cc: "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: Wed, 25 Oct 2017 21:57:23 -0700	[thread overview]
Message-ID: <1508993843.10651.22.camel@perches.com> (raw)
In-Reply-To: <1508986436-31966-2-git-send-email-me@tobin.cc>

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()

> Remove the attempt to print NULL pointers with a correct width.

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

> Signed-off-by: Tobin C. Harding <me@tobin.cc>
> ---
>  lib/vsprintf.c | 9 +--------
>  1 file changed, 1 insertion(+), 8 deletions(-)
> 
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> index 86c3385b9eb3..16a587aed40e 100644
> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> @@ -1710,15 +1710,8 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
>  {
>  	const int default_width = 2 * sizeof(void *);
>  
> -	if (!ptr && *fmt != 'K') {
> -		/*
> -		 * Print (null) with the same width as a pointer so it makes
> -		 * tabular output look nice.
> -		 */
> -		if (spec.field_width == -1)
> -			spec.field_width = default_width;
> +	if (!ptr && *fmt != 'K')
>  		return string(buf, end, "(null)", spec);
> -	}
>  
>  	switch (*fmt) {
>  	case 'F':

  reply	other threads:[~2017-10-26  4:57 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-26  2:53 [PATCH V8 0/2] printk: hash addresses printed with %p Tobin C. Harding
2017-10-26  2:53 ` [PATCH V8 1/2] printk: remove tabular output for NULL pointer Tobin C. Harding
2017-10-26  4:57   ` Joe Perches [this message]
2017-10-26  6:27     ` Tobin C. Harding
2017-10-26  8:05       ` Joe Perches
2017-10-26  9:37         ` Tobin C. Harding
2017-10-26 14:47           ` Joe Perches
2017-10-26 23:57             ` Tobin C. Harding
2017-10-27  0:11               ` Joe Perches
2017-10-26  2:53 ` [PATCH V8 2/2] printk: hash addresses printed with %p Tobin C. Harding
2017-10-26  2:58   ` Tobin C. Harding
2017-10-30 21:33     ` Steven Rostedt
2017-10-30 22:41       ` Tobin C. Harding
2017-10-31  0:00         ` Steven Rostedt
2017-10-31  2:00           ` Tobin C. Harding
2017-10-26  3:11   ` Jason A. Donenfeld
2017-10-27 13:33 ` [PATCH V8 0/2] " Sergey Senozhatsky
2017-10-31 23:35   ` Tobin C. Harding
2017-11-02  8:23     ` Sergey Senozhatsky
2017-11-02 10:14       ` Tobin C. Harding
2017-11-02 13:43         ` Roberts, William C
2017-11-02 16:04         ` Sergey Senozhatsky
2017-10-30 22:03 ` Kees Cook
2017-10-30 22:33   ` Tobin C. Harding
2017-10-31  2:08     ` Joe Perches
2017-10-31 23:16       ` Tobin C. Harding
2017-10-31 23:33         ` Joe Perches
2017-11-03  5:13           ` Vinod Koul

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