Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1302905 > unrolled thread

Re: [PATCH 3/5] x86: simplify early command line parsing

Back to article view | Back to linux.kernel

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.

Contents

  Re: [PATCH 3/5] x86: simplify early command line parsing Borislav Petkov <bp@suse.de> - 2016-01-06 18:20 +0100
    Re: [PATCH 3/5] x86: simplify early command line parsing Dave Hansen <dave@sr71.net> - 2016-01-06 18:40 +0100
      Re: [PATCH 3/5] x86: simplify early command line parsing Borislav Petkov <bp@suse.de> - 2016-01-06 18:50 +0100
    Re: [PATCH 3/5] x86: simplify early command line parsing Dave Hansen <dave@sr71.net> - 2016-01-06 18:40 +0100

#1302905 — Re: [PATCH 3/5] x86: simplify early command line parsing

On Tue, Dec 22, 2015 at 02:52:41PM -0800, Dave Hansen wrote:
> 
> From: Dave Hansen <dave.hansen@linux.intel.com>
> 
> __cmdline_find_option_bool() tries to account for both
> NULL-terminated and non-NULL-terminated strings.  It keeps 'pos'
> to look for the end of the buffer and also looks for '!c' in a
> bunch of places to look for NULL termination.
> 
> But, it also calls strlen().  You can't call strlen on a
> non-NULL-terminated string.
> 
> If !strlen(cmdline), then cmdline[0]=='\0'.  In that case, we
> will go in to the while() loop, set c='\0', hit st_wordstart,
> notice !c, and will immediately return 0.
> 
> So, remove the strlen().  It is unnecessary and unsafe.
> 
> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
> Cc: Borislav Petkov <bp@suse.de>
> Cc: H. Peter Anvin <hpa@zytor.com>
> Cc: linux-kernel@vger.kernel.org
> Cc: fenghua.yu@intel.com
> Cc: yu-cheng.yu@intel.com
> ---
> 
>  b/arch/x86/lib/cmdline.c |    3 ---
>  1 file changed, 3 deletions(-)
> 
> diff -puN arch/x86/lib/cmdline.c~x86-early-command-line-non-term arch/x86/lib/cmdline.c
> --- a/arch/x86/lib/cmdline.c~x86-early-command-line-non-term	2015-12-22 11:56:59.454186167 -0800
> +++ b/arch/x86/lib/cmdline.c	2015-12-22 11:56:59.457186302 -0800
> @@ -39,9 +39,6 @@ int cmdline_find_option_bool(const char
>  	if (!cmdline)
>  		return -1;      /* No command line */
>  
> -	if (!strlen(cmdline))
> -		return 0;
> -

Patch 1 adds the strlen(), this patch removes it. Please merge both patches.

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
-- 
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[toc] | [next] | [standalone]

#1302915

On 01/06/2016 09:10 AM, Borislav Petkov wrote:
>> > -	if (!strlen(cmdline))
>> > -		return 0;
>> > -
> Patch 1 adds the strlen(), this patch removes it. Please merge both patches.

As I mentioned, it doesn't strictly add it.

Plus, if I go add this back to that patch, I'll end up having to paste
most of the changelog in to that one.  I think it's much more clear to
have this hunk live on its own.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[toc] | [prev] | [next] | [standalone]

#1302930

On Wed, Jan 06, 2016 at 09:37:40AM -0800, Dave Hansen wrote:
> On 01/06/2016 09:10 AM, Borislav Petkov wrote:
> >> > -	if (!strlen(cmdline))
> >> > -		return 0;
> >> > -
> > Patch 1 adds the strlen(), this patch removes it. Please merge both patches.
> 
> As I mentioned, it doesn't strictly add it.
> 
> Plus, if I go add this back to that patch, I'll end up having to paste
> most of the changelog in to that one.  I think it's much more clear to
> have this hunk live on its own.

So why not leave the min_t:

	maxlen = min_t(int, strlen(cmdline), COMMAND_LINE_SIZE);

and then do:

	while (pos < maxlen)

?

This way it is absolutely clear what's going on.

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
-- 
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[toc] | [prev] | [next] | [standalone]

#1302918

On 01/06/2016 09:10 AM, Borislav Petkov wrote:
>> > diff -puN arch/x86/lib/cmdline.c~x86-early-command-line-non-term arch/x86/lib/cmdline.c
>> > --- a/arch/x86/lib/cmdline.c~x86-early-command-line-non-term	2015-12-22 11:56:59.454186167 -0800
>> > +++ b/arch/x86/lib/cmdline.c	2015-12-22 11:56:59.457186302 -0800
>> > @@ -39,9 +39,6 @@ int cmdline_find_option_bool(const char
>> >  	if (!cmdline)
>> >  		return -1;      /* No command line */
>> >  
>> > -	if (!strlen(cmdline))
>> > -		return 0;
>> > -
> Patch 1 adds the strlen(), this patch removes it. Please merge both patches.

Yes, it adds a line that uses strlen.  But, there was already the use in
the min_t() "call":

> -	len = min_t(int, strlen(cmdline), COMMAND_LINE_SIZE);
> -	if (!len)
> +	if (!strlen(cmdline))
>  		return 0;

I wanted to separate the two things because they really fix two separate
issues.  I also want to ensure that any problems that this patch causes
can be isolated to the smallest change possible.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web