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RE: [PATCH] checkpatch: add warning on %pk instead of %pK usage

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  RE: [PATCH] checkpatch: add warning on %pk instead of %pK usage "Roberts, William C" <william.c.roberts@intel.com> - 2017-02-13 20:50 +0100
    Re: [PATCH] checkpatch: add warning on %pk instead of %pK usage Joe Perches <joe@perches.com> - 2017-02-13 21:20 +0100
    Re: [PATCH] checkpatch: add warning on %pk instead of %pK usage Joe Perches <joe@perches.com> - 2017-02-13 23:30 +0100
      RE: [PATCH] checkpatch: add warning on %pk instead of %pK usage "Roberts, William C" <william.c.roberts@intel.com> - 2017-02-16 00:50 +0100
        Re: [PATCH] checkpatch: add warning on %pk instead of %pK usage Joe Perches <joe@perches.com> - 2017-02-16 01:30 +0100
        RE: [PATCH] checkpatch: add warning on %pk instead of %pK usage "Roberts, William C" <william.c.roberts@intel.com> - 2017-02-27 17:30 +0100
          [PATCH] checkpatch: Add ability to find bad uses of vsprintf %p<foo> extensions Joe Perches <joe@perches.com> - 2017-02-27 22:00 +0100
            Re: [kernel-hardening] [PATCH] checkpatch: Add ability to find bad  uses of vsprintf %p<foo> extensions Kees Cook <keescook@chromium.org> - 2017-02-27 22:40 +0100
            RE: [PATCH] checkpatch: Add ability to find bad uses of vsprintf  %p<foo> extensions "Roberts, William C" <william.c.roberts@intel.com> - 2017-02-28 16:40 +0100
            Re: [PATCH] checkpatch: Add ability to find bad uses of vsprintf  %p<foo> extensions Joe Perches <joe@perches.com> - 2017-03-01 01:20 +0100
            Re: [kernel-hardening] Re: [PATCH] checkpatch: Add ability to find  bad uses of vsprintf %p<foo> extensions Kees Cook <keescook@chromium.org> - 2017-03-01 01:20 +0100
              Re: [kernel-hardening] Re: [PATCH] checkpatch: Add ability to find  bad uses of vsprintf %p<foo> extensions Joe Perches <joe@perches.com> - 2017-03-01 02:30 +0100
            Re: [PATCH] checkpatch: Add ability to find bad uses of vsprintf  %p<foo> extensions Andrew Morton <akpm@linux-foundation.org> - 2017-03-01 03:10 +0100

#1580043 — RE: [PATCH] checkpatch: add warning on %pk instead of %pK usage

> -----Original Message-----
> From: Joe Perches [mailto:joe@perches.com]
> Sent: Friday, February 10, 2017 7:24 PM
> To: Roberts, William C <william.c.roberts@intel.com>; linux-
> kernel@vger.kernel.org; apw@canonical.com
> Cc: kernel-hardening@lists.openwall.com
> Subject: Re: [PATCH] checkpatch: add warning on %pk instead of %pK usage
> 
> On Sat, 2017-02-11 at 01:32 +0000, Roberts, William C wrote:
> > <snip>
> > > > By "normal" I'm referring to things that call into pointer(), just
> > > > casually looking I see bstr_printf vsnprintf kvasprintf, which
> > > > would be easy enough to add
> > > >
> > > > > What do you think is missing?  sn?printf ? That's easy to add.
> > > >
> > > > The problem starts to get hairy when we think of how often folks
> > > > roll their own logging macros (see some small sampling at the end).
> > > >
> > > > I think we would want to add DEBUG DBG and sn?printf and maybe
> > > > consider dropping the \b on the regex so it's a bit more matchy
> > > > but still shouldn't end up matching on any ASM as you pointed out in the V2
> nack.
> > > >
> > > > Ill break this down into:
> > > > 1. the patch as I know you'll take it, as you wrote it :-P 2.
> > > > Adding to the logging macros 3. exploring making it less matchy
> >
> > -Kees and Andrew they likely don't care about the rest of this...
> >
> > I have been working up a regex (I suck at these) to match C functions
> > that have an invalid %p format string and take arguments:
> > http://www.regexr.com/3f92k
> >
> > This could be a way to get better coverage in a more generic approach,
> thoughts?
> 
> Maybe this: (attached too because Evolution is a bad email client)
> 
> It's still kind of hacky, but it does find multiple line statements like:
> 
> +		printf(KERN_INFO
> +		       "a %pX",
> +		       foo);
> 

I downloaded your checkpatch.pl patch wouldn't apply for some reason... I applied it by hand and
couldn't get it to trigger on either the case you show above or below:

+	MY_DEBUG(drv->foo,
+		"%pk",
+		foo->boo);
+

> ---
> Subject: [PATCH] checkpatch: Add ability to find bad uses of vsprintf %p
> extensions
> 
> %pK was at least once misused at %pk in an out-of-tree module.
> This lead to some security concerns.  Add the ability to track single and multiple
> line statements for misuses of %p.
> 
> Signed-off-by: Joe Perches
> ---
>  scripts/checkpatch.pl | 26 ++++++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
> 
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index
> ad5ea5c545b2..0eaf6b8580d6 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -5676,6 +5676,32 @@ sub process {
>  			}
>  		}
> 
> +		# check for vsprintf extension %p misuses
> +		if ($^V && $^V ge 5.10.0 &&
> +		    defined $stat &&
> +		    $stat =~ /^\+(?![^\{]*\{\s*).*\b(\w+)\s*\(.*$String\s*,/s &&
> +		    $1 !~ /^_*volatile_*$/) {
> +			my $bad_extension = "";
> +			my $lc = $stat =~ tr@\n@@;
> +			$lc = $lc + $linenr;
> +		        for (my $count = $linenr; $count <= $lc; $count++) {
> +				my $fmt = get_quoted_string($lines[$count - 1],
> raw_line($count, 0));
> +				$fmt =~ s/%%//g;
> +				if ($fmt =~
> /(\%[\*\d\.]*p(?![\WFfSsBKRraEhMmIiUDdgVCbGN]).)/) {
> +					$bad_extension = $1;
> +					last;
> +				}
> +			}
> +			if ($bad_extension ne "") {
> +				my $stat_real = raw_line($linenr, 0);
> +				for (my $count = $linenr + 1; $count <= $lc;
> $count++) {
> +					$stat_real = $stat_real . "\n" .
> raw_line($count, 0);
> +				}
> +				WARN("VSPRINTF_POINTER_EXTENSION",
> +				     "Invalid vsprintf pointer extension
> '$bad_extension'\n" . "$here\n$stat_real\n");
> +			}
> +		}
> +
>  # Check for misused memsets
>  		if ($^V && $^V ge 5.10.0 &&
>  		    defined $stat &&
> --

Mixed tabs/spaces issues. But I like the concept of matching across multiple lines. My tree was set to:

commit 7089db84e356562f8ba737c29e472cc42d530dbc
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date:   Sun Feb 12 13:03:20 2017 -0800

    Linux 4.10-rc8

$ git apply --check ~/Downloads/0001-checkpatch-Add-ability-to-find-bad-uses-of-vsprintf-.patch
error: patch failed: scripts/checkpatch.pl:5676
error: scripts/checkpatch.pl: patch does not apply

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#1580053

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(resending including cc's)

On Mon, 2017-02-13 at 19:46 +0000, Roberts, William C wrote:
> > -----Original Message-----
> > From: Joe Perches [mailto:joe@perches.com]
> > Sent: Friday, February 10, 2017 7:24 PM
> > To: Roberts, William C <william.c.roberts@intel.com>; linux-
> > kernel@vger.kernel.org; apw@canonical.com
> > Cc: kernel-hardening@lists.openwall.com
> > Subject: Re: [PATCH] checkpatch: add warning on %pk instead of %pK usage
> > 
> > On Sat, 2017-02-11 at 01:32 +0000, Roberts, William C wrote:
> > > <snip>
> > > > > By "normal" I'm referring to things that call into pointer(), just
> > > > > casually looking I see bstr_printf vsnprintf kvasprintf, which
> > > > > would be easy enough to add
> > > > > 
> > > > > > What do you think is missing?  sn?printf ? That's easy to add.
> > > > > 
> > > > > The problem starts to get hairy when we think of how often folks
> > > > > roll their own logging macros (see some small sampling at the end).
> > > > > 
> > > > > I think we would want to add DEBUG DBG and sn?printf and maybe
> > > > > consider dropping the \b on the regex so it's a bit more matchy
> > > > > but still shouldn't end up matching on any ASM as you pointed out in the V2
> > 
> > nack.
> > > > > 
> > > > > Ill break this down into:
> > > > > 1. the patch as I know you'll take it, as you wrote it :-P 2.
> > > > > Adding to the logging macros 3. exploring making it less matchy
> > > 
> > > -Kees and Andrew they likely don't care about the rest of this...
> > > 
> > > I have been working up a regex (I suck at these) to match C functions
> > > that have an invalid %p format string and take arguments:
> > > http://www.regexr.com/3f92k
> > > 
> > > This could be a way to get better coverage in a more generic approach,
> > 
> > thoughts?
> > 
> > Maybe this: (attached too because Evolution is a bad email client)
> > 
> > It's still kind of hacky, but it does find multiple line statements like:
> > 
> > +		printf(KERN_INFO
> > +		       "a %pX",
> > +		       foo);
> > 
> 
> I downloaded your checkpatch.pl patch wouldn't apply for some reason... I applied it by hand and
> couldn't get it to trigger on either the case you show above or below:
> 
> +	MY_DEBUG(drv->foo,
> +		"%pk",
> +		foo->boo);
> +
> 
> > ---
> > Subject: [PATCH] checkpatch: Add ability to find bad uses of vsprintf %p
> > extensions
> > 
> > %pK was at least once misused at %pk in an out-of-tree module.
> > This lead to some security concerns.  Add the ability to track single and multiple
> > line statements for misuses of %p.
> > 
> > Signed-off-by: Joe Perches
> > ---
> >  scripts/checkpatch.pl | 26 ++++++++++++++++++++++++++
> >  1 file changed, 26 insertions(+)
> > 
> > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index
> > ad5ea5c545b2..0eaf6b8580d6 100755
> > --- a/scripts/checkpatch.pl
> > +++ b/scripts/checkpatch.pl
> > @@ -5676,6 +5676,32 @@ sub process {
> >  			}
> >  		}
> > 
> > +		# check for vsprintf extension %p misuses
> > +		if ($^V && $^V ge 5.10.0 &&
> > +		    defined $stat &&
> > +		    $stat =~ /^\+(?![^\{]*\{\s*).*\b(\w+)\s*\(.*$String\s*,/s &&
> > +		    $1 !~ /^_*volatile_*$/) {
> > +			my $bad_extension = "";
> > +			my $lc = $stat =~ tr@\n@@;
> > +			$lc = $lc + $linenr;
> > +		        for (my $count = $linenr; $count <= $lc; $count++) {
> > +				my $fmt = get_quoted_string($lines[$count - 1],
> > raw_line($count, 0));
> > +				$fmt =~ s/%%//g;
> > +				if ($fmt =~
> > /(\%[\*\d\.]*p(?![\WFfSsBKRraEhMmIiUDdgVCbGN]).)/) {
> > +					$bad_extension = $1;
> > +					last;
> > +				}
> > +			}
> > +			if ($bad_extension ne "") {
> > +				my $stat_real = raw_line($linenr, 0);
> > +				for (my $count = $linenr + 1; $count <= $lc;
> > $count++) {
> > +					$stat_real = $stat_real . "\n" .
> > raw_line($count, 0);
> > +				}
> > +				WARN("VSPRINTF_POINTER_EXTENSION",
> > +				     "Invalid vsprintf pointer extension
> > '$bad_extension'\n" . "$here\n$stat_real\n");
> > +			}
> > +		}
> > +
> >  # Check for misused memsets
> >  		if ($^V && $^V ge 5.10.0 &&
> >  		    defined $stat &&
> > --
> 
> Mixed tabs/spaces issues. But I like the concept of matching across multiple lines. My tree was set to:
> 
> commit 7089db84e356562f8ba737c29e472cc42d530dbc
> Author: Linus Torvalds <torvalds@linux-foundation.org>
> Date:   Sun Feb 12 13:03:20 2017 -0800
> 
>     Linux 4.10-rc8
> 
> $ git apply --check ~/Downloads/0001-checkpatch-Add-ability-to-find-bad-uses-of-vsprintf-.patch
> error: patch failed: scripts/checkpatch.pl:5676
> error: scripts/checkpatch.pl: patch does not apply
> 

No worries.
No idea why it doesn't work for you.
Maybe the hand applying was somehow
faulty?

The attached is on top of -next so it does have offsets
on Linus' tree, but it seems to work.

(on -linux)

$ patch -p1 < cp_vsp.diff 
patching file scripts/checkpatch.pl
Hunk #1 succeeded at 5634 (offset -36 lines).

$ cat t_block.c
{
	MY_DEBUG(drv->foo,
		 "%pk",
		 foo->boo);
}
$ ./scripts/checkpatch.pl -f t_block.c
WARNING: Invalid vsprintf pointer extension '%pk'
#2: FILE: t_block.c:2:
+	MY_DEBUG(drv->foo,
+		 "%pk",
+		 foo->boo);

total: 0 errors, 1 warnings, 5 lines checked

NOTE: For some of the reported defects, checkpatch may be able to
      mechanically convert to the typical style using --fix or --fix-inplace.

t_block.c has style problems, please review.

NOTE: If any of the errors are false positives, please report
      them to the maintainer, see CHECKPATCH in MAINTAINERS.

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#1580117

[Multipart message — attachments visible in raw view] — view raw

(Adding back the cc's)

On Mon, 2017-02-13 at 21:28 +0000, Roberts, William C wrote:
> <snip>
> > No worries.
> > No idea why it doesn't work for you.
> > Maybe the hand applying was somehow
> > faulty?
> > 
> > The attached is on top of -next so it does have offsets on Linus' tree, but it seems
> > to work.
> > 
> > (on -linux)
> > 
> > $ patch -p1 < cp_vsp.diff
> > patching file scripts/checkpatch.pl
> > Hunk #1 succeeded at 5634 (offset -36 lines).
> > 
> > $ cat t_block.c
> > {
> > 	MY_DEBUG(drv->foo,
> > 		 "%pk",
> > 		 foo->boo);
> > }
> > $ ./scripts/checkpatch.pl -f t_block.c
> > WARNING: Invalid vsprintf pointer extension '%pk'
> > #2: FILE: t_block.c:2:
> > +	MY_DEBUG(drv->foo,
> > +		 "%pk",
> > +		 foo->boo);
> > 
> > total: 0 errors, 1 warnings, 5 lines checked
> > 
> > NOTE: For some of the reported defects, checkpatch may be able to
> >       mechanically convert to the typical style using --fix or --fix-inplace.
> > 
> > t_block.c has style problems, please review.
> > 
> > NOTE: If any of the errors are false positives, please report
> >       them to the maintainer, see CHECKPATCH in MAINTAINERS.
> 
> 
> Applied. It works fine with your example (see attached 0001-tblock.patch) but it doesn't provide
> Output for me with 0002-drv-hack.patch (attached as well)
> 
> $ ./scripts/checkpatch.pl 0002-drv-hack.patch 
> total: 0 errors, 0 warnings, 10 lines checked
> 
> 0002-drv-hack.patch has no obvious style problems and is ready for submission.
> 
> ./scripts/checkpatch.pl 0001-tblock.patch 
> WARNING: added, moved or deleted file(s), does MAINTAINERS need updating?
> #13: 
> new file mode 100644
> 
> WARNING: Invalid vsprintf pointer extension '%pk'
> #19: FILE: t_block.c:2:
> +	MY_DEBUG(drv->foo,
> +		"%pk",
> +		 foo->boo);
> 
> total: 0 errors, 2 warnings, 6 lines checked
> 
> NOTE: For some of the reported defects, checkpatch may be able to
>       mechanically convert to the typical style using --fix or --fix-inplace.
> 
> 0001-tblock.patch has style problems, please review.
> 
> NOTE: If any of the errors are false positives, please report
>       them to the maintainer, see CHECKPATCH in MAINTAINERS.

This means _all_ the $stat checks aren't being done
on patches that add just a single multi-line statement.

Andrew?  Any thoughts on how to enable $stat appropriately
for patch contexts with a single multi-line statement?

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#1582047

> -----Original Message-----
> From: Joe Perches [mailto:joe@perches.com]
> Sent: Monday, February 13, 2017 2:21 PM
> To: Roberts, William C <william.c.roberts@intel.com>
> Cc: linux-kernel@vger.kernel.org; apw@canonical.com; kernel-
> hardening@lists.openwall.com
> Subject: Re: [PATCH] checkpatch: add warning on %pk instead of %pK usage
> 
> (Adding back the cc's)
> 
> On Mon, 2017-02-13 at 21:28 +0000, Roberts, William C wrote:
> > <snip>
> > > No worries.
> > > No idea why it doesn't work for you.
> > > Maybe the hand applying was somehow
> > > faulty?
> > >
> > > The attached is on top of -next so it does have offsets on Linus'
> > > tree, but it seems to work.
> > >
> > > (on -linux)
> > >
> > > $ patch -p1 < cp_vsp.diff
> > > patching file scripts/checkpatch.pl
> > > Hunk #1 succeeded at 5634 (offset -36 lines).
> > >
> > > $ cat t_block.c
> > > {
> > > 	MY_DEBUG(drv->foo,
> > > 		 "%pk",
> > > 		 foo->boo);
> > > }
> > > $ ./scripts/checkpatch.pl -f t_block.c
> > > WARNING: Invalid vsprintf pointer extension '%pk'
> > > #2: FILE: t_block.c:2:
> > > +	MY_DEBUG(drv->foo,
> > > +		 "%pk",
> > > +		 foo->boo);
> > >
> > > total: 0 errors, 1 warnings, 5 lines checked
> > >
> > > NOTE: For some of the reported defects, checkpatch may be able to
> > >       mechanically convert to the typical style using --fix or --fix-inplace.
> > >
> > > t_block.c has style problems, please review.
> > >
> > > NOTE: If any of the errors are false positives, please report
> > >       them to the maintainer, see CHECKPATCH in MAINTAINERS.
> >
> >
> > Applied. It works fine with your example (see attached
> > 0001-tblock.patch) but it doesn't provide Output for me with
> > 0002-drv-hack.patch (attached as well)
> >
> > $ ./scripts/checkpatch.pl 0002-drv-hack.patch
> > total: 0 errors, 0 warnings, 10 lines checked
> >
> > 0002-drv-hack.patch has no obvious style problems and is ready for submission.
> >
> > ./scripts/checkpatch.pl 0001-tblock.patch
> > WARNING: added, moved or deleted file(s), does MAINTAINERS need
> updating?
> > #13:
> > new file mode 100644
> >
> > WARNING: Invalid vsprintf pointer extension '%pk'
> > #19: FILE: t_block.c:2:
> > +	MY_DEBUG(drv->foo,
> > +		"%pk",
> > +		 foo->boo);
> >
> > total: 0 errors, 2 warnings, 6 lines checked
> >
> > NOTE: For some of the reported defects, checkpatch may be able to
> >       mechanically convert to the typical style using --fix or --fix-inplace.
> >
> > 0001-tblock.patch has style problems, please review.
> >
> > NOTE: If any of the errors are false positives, please report
> >       them to the maintainer, see CHECKPATCH in MAINTAINERS.
> 
> This means _all_ the $stat checks aren't being done on patches that add just a
> single multi-line statement.
> 
> Andrew?  Any thoughts on how to enable $stat appropriately for patch contexts
> with a single multi-line statement?

I'm for merging your patch as is, and then take up the fact that $stat is not working correctly
as a separate change, does that seem reasonable?

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#1582130

On Wed, 2017-02-15 at 23:49 +0000, Roberts, William C wrote:
> > 
> > This means _all_ the $stat checks aren't being done on patches that add just a
> > single multi-line statement.
> > 
> > Andrew?  Any thoughts on how to enable $stat appropriately for patch contexts
> > with a single multi-line statement?
> 
> I'm for merging your patch as is, and then take up the fact that $stat is not working correctly
> as a separate change, does that seem reasonable?

Sure, Andrew Morton is the typical upstream path for checkpatch.
(cc'd)

Andy Whitcroft?  Any chance to look at this?

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#1588794

> -----Original Message-----
> From: Roberts, William C [mailto:william.c.roberts@intel.com]
> Sent: Wednesday, February 15, 2017 3:49 PM
> To: Joe Perches <joe@perches.com>
> Cc: linux-kernel@vger.kernel.org; apw@canonical.com; kernel-
> hardening@lists.openwall.com
> Subject: [kernel-hardening] RE: [PATCH] checkpatch: add warning on %pk instead
> of %pK usage
> 
> 
> 
> > -----Original Message-----
> > From: Joe Perches [mailto:joe@perches.com]
> > Sent: Monday, February 13, 2017 2:21 PM
> > To: Roberts, William C <william.c.roberts@intel.com>
> > Cc: linux-kernel@vger.kernel.org; apw@canonical.com; kernel-
> > hardening@lists.openwall.com
> > Subject: Re: [PATCH] checkpatch: add warning on %pk instead of %pK
> > usage
> >
> > (Adding back the cc's)
> >
> > On Mon, 2017-02-13 at 21:28 +0000, Roberts, William C wrote:
> > > <snip>
> > > > No worries.
> > > > No idea why it doesn't work for you.
> > > > Maybe the hand applying was somehow faulty?
> > > >
> > > > The attached is on top of -next so it does have offsets on Linus'
> > > > tree, but it seems to work.
> > > >
> > > > (on -linux)
> > > >
> > > > $ patch -p1 < cp_vsp.diff
> > > > patching file scripts/checkpatch.pl Hunk #1 succeeded at 5634
> > > > (offset -36 lines).
> > > >
> > > > $ cat t_block.c
> > > > {
> > > > 	MY_DEBUG(drv->foo,
> > > > 		 "%pk",
> > > > 		 foo->boo);
> > > > }
> > > > $ ./scripts/checkpatch.pl -f t_block.c
> > > > WARNING: Invalid vsprintf pointer extension '%pk'
> > > > #2: FILE: t_block.c:2:
> > > > +	MY_DEBUG(drv->foo,
> > > > +		 "%pk",
> > > > +		 foo->boo);
> > > >
> > > > total: 0 errors, 1 warnings, 5 lines checked
> > > >
> > > > NOTE: For some of the reported defects, checkpatch may be able to
> > > >       mechanically convert to the typical style using --fix or --fix-inplace.
> > > >
> > > > t_block.c has style problems, please review.
> > > >
> > > > NOTE: If any of the errors are false positives, please report
> > > >       them to the maintainer, see CHECKPATCH in MAINTAINERS.
> > >
> > >
> > > Applied. It works fine with your example (see attached
> > > 0001-tblock.patch) but it doesn't provide Output for me with
> > > 0002-drv-hack.patch (attached as well)
> > >
> > > $ ./scripts/checkpatch.pl 0002-drv-hack.patch
> > > total: 0 errors, 0 warnings, 10 lines checked
> > >
> > > 0002-drv-hack.patch has no obvious style problems and is ready for
> submission.
> > >
> > > ./scripts/checkpatch.pl 0001-tblock.patch
> > > WARNING: added, moved or deleted file(s), does MAINTAINERS need
> > updating?
> > > #13:
> > > new file mode 100644
> > >
> > > WARNING: Invalid vsprintf pointer extension '%pk'
> > > #19: FILE: t_block.c:2:
> > > +	MY_DEBUG(drv->foo,
> > > +		"%pk",
> > > +		 foo->boo);
> > >
> > > total: 0 errors, 2 warnings, 6 lines checked
> > >
> > > NOTE: For some of the reported defects, checkpatch may be able to
> > >       mechanically convert to the typical style using --fix or --fix-inplace.
> > >
> > > 0001-tblock.patch has style problems, please review.
> > >
> > > NOTE: If any of the errors are false positives, please report
> > >       them to the maintainer, see CHECKPATCH in MAINTAINERS.
> >
> > This means _all_ the $stat checks aren't being done on patches that
> > add just a single multi-line statement.
> >
> > Andrew?  Any thoughts on how to enable $stat appropriately for patch
> > contexts with a single multi-line statement?
> 
> I'm for merging your patch as is, and then take up the fact that $stat is not
> working correctly as a separate change, does that seem reasonable?

I haven't seen anything on list about your patch, are we kind of stuck or do you
have some plan on adding your stat patch in the future?

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#1588943 — [PATCH] checkpatch: Add ability to find bad uses of vsprintf %p<foo> extensions

%pK was at least once misused at %pk in an out-of-tree module.
This lead to some security concerns.  Add the ability to track
single and multiple line statements for misuses of %p<foo>.

Signed-off-by: Joe Perches <joe@perches.com>
---

Andrew, this has gone back and forth a few times.

It's imperfect as a patch context with just a single
function addition can be missed, but that's not new
with $stat tests and just this patch.  Perhaps one day
the $stat identification mechanism can be improved.

Until then, can you please apply this?  Thanks.

 scripts/checkpatch.pl | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index ad5ea5c545b2..9293b8a1c121 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -5676,6 +5676,32 @@ sub process {
 			}
 		}
 
+		# check for vsprintf extension %p<foo> misuses
+		if ($^V && $^V ge 5.10.0 &&
+		    defined $stat &&
+		    $stat =~ /^\+(?![^\{]*\{\s*).*\b(\w+)\s*\(.*$String\s*,/s &&
+		    $1 !~ /^_*volatile_*$/) {
+			my $bad_extension = "";
+			my $lc = $stat =~ tr@\n@@;
+			$lc = $lc + $linenr;
+		        for (my $count = $linenr; $count <= $lc; $count++) {
+				my $fmt = get_quoted_string($lines[$count - 1], raw_line($count, 0));
+				$fmt =~ s/%%//g;
+				if ($fmt =~ /(\%[\*\d\.]*p(?![\WFfSsBKRraEhMmIiUDdgVCbGN]).)/) {
+					$bad_extension = $1;
+					last;
+				}
+			}
+			if ($bad_extension ne "") {
+				my $stat_real = raw_line($linenr, 0);
+				for (my $count = $linenr + 1; $count <= $lc; $count++) {
+					$stat_real = $stat_real . "\n" . raw_line($count, 0);
+				}
+				WARN("VSPRINTF_POINTER_EXTENSION",
+				     "Invalid vsprintf pointer extension '$bad_extension'\n" . "$here\n$stat_real\n");
+			}
+		}
+
 # Check for misused memsets
 		if ($^V && $^V ge 5.10.0 &&
 		    defined $stat &&
-- 
2.10.0.rc2.1.g053435c

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#1588959 — Re: [kernel-hardening] [PATCH] checkpatch: Add ability to find bad uses of vsprintf %p<foo> extensions

On Mon, Feb 27, 2017 at 12:54 PM, Joe Perches <joe@perches.com> wrote:
> %pK was at least once misused at %pk in an out-of-tree module.
> This lead to some security concerns.  Add the ability to track
> single and multiple line statements for misuses of %p<foo>.
>
> Signed-off-by: Joe Perches <joe@perches.com>

Acked-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>
> Andrew, this has gone back and forth a few times.
>
> It's imperfect as a patch context with just a single
> function addition can be missed, but that's not new
> with $stat tests and just this patch.  Perhaps one day
> the $stat identification mechanism can be improved.
>
> Until then, can you please apply this?  Thanks.
>
>  scripts/checkpatch.pl | 26 ++++++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
>
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index ad5ea5c545b2..9293b8a1c121 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -5676,6 +5676,32 @@ sub process {
>                         }
>                 }
>
> +               # check for vsprintf extension %p<foo> misuses
> +               if ($^V && $^V ge 5.10.0 &&
> +                   defined $stat &&
> +                   $stat =~ /^\+(?![^\{]*\{\s*).*\b(\w+)\s*\(.*$String\s*,/s &&
> +                   $1 !~ /^_*volatile_*$/) {
> +                       my $bad_extension = "";
> +                       my $lc = $stat =~ tr@\n@@;
> +                       $lc = $lc + $linenr;
> +                       for (my $count = $linenr; $count <= $lc; $count++) {
> +                               my $fmt = get_quoted_string($lines[$count - 1], raw_line($count, 0));
> +                               $fmt =~ s/%%//g;
> +                               if ($fmt =~ /(\%[\*\d\.]*p(?![\WFfSsBKRraEhMmIiUDdgVCbGN]).)/) {
> +                                       $bad_extension = $1;
> +                                       last;
> +                               }
> +                       }
> +                       if ($bad_extension ne "") {
> +                               my $stat_real = raw_line($linenr, 0);
> +                               for (my $count = $linenr + 1; $count <= $lc; $count++) {
> +                                       $stat_real = $stat_real . "\n" . raw_line($count, 0);
> +                               }
> +                               WARN("VSPRINTF_POINTER_EXTENSION",
> +                                    "Invalid vsprintf pointer extension '$bad_extension'\n" . "$here\n$stat_real\n");
> +                       }
> +               }
> +
>  # Check for misused memsets
>                 if ($^V && $^V ge 5.10.0 &&
>                     defined $stat &&
> --
> 2.10.0.rc2.1.g053435c
>



-- 
Kees Cook
Pixel Security

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#1589574 — RE: [PATCH] checkpatch: Add ability to find bad uses of vsprintf %p<foo> extensions

> -----Original Message-----
> From: Joe Perches [mailto:joe@perches.com]
> Sent: Monday, February 27, 2017 12:55 PM
> To: Andrew Morton <akpm@linux-foundation.org>; Andy Whitcroft
> <apw@canonical.com>
> Cc: Roberts, William C <william.c.roberts@intel.com>; kernel-
> hardening@lists.openwall.com; linux-kernel@vger.kernel.org
> Subject: [PATCH] checkpatch: Add ability to find bad uses of vsprintf %p<foo>
> extensions
> 
> %pK was at least once misused at %pk in an out-of-tree module.
> This lead to some security concerns.  Add the ability to track single and multiple
> line statements for misuses of %p<foo>.
> 
> Signed-off-by: Joe Perches <joe@perches.com>

Acked-By: William Roberts <william.c.roberts@intel.com>

> ---
> 
> Andrew, this has gone back and forth a few times.
> 
> It's imperfect as a patch context with just a single function addition can be
> missed, but that's not new with $stat tests and just this patch.  Perhaps one day
> the $stat identification mechanism can be improved.
> 
> Until then, can you please apply this?  Thanks.
> 
>  scripts/checkpatch.pl | 26 ++++++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
> 
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index
> ad5ea5c545b2..9293b8a1c121 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -5676,6 +5676,32 @@ sub process {
>  			}
>  		}
> 
> +		# check for vsprintf extension %p<foo> misuses
> +		if ($^V && $^V ge 5.10.0 &&
> +		    defined $stat &&
> +		    $stat =~ /^\+(?![^\{]*\{\s*).*\b(\w+)\s*\(.*$String\s*,/s &&
> +		    $1 !~ /^_*volatile_*$/) {
> +			my $bad_extension = "";
> +			my $lc = $stat =~ tr@\n@@;
> +			$lc = $lc + $linenr;
> +		        for (my $count = $linenr; $count <= $lc; $count++) {
> +				my $fmt = get_quoted_string($lines[$count - 1],
> raw_line($count, 0));
> +				$fmt =~ s/%%//g;
> +				if ($fmt =~
> /(\%[\*\d\.]*p(?![\WFfSsBKRraEhMmIiUDdgVCbGN]).)/) {
> +					$bad_extension = $1;
> +					last;
> +				}
> +			}
> +			if ($bad_extension ne "") {
> +				my $stat_real = raw_line($linenr, 0);
> +				for (my $count = $linenr + 1; $count <= $lc;
> $count++) {
> +					$stat_real = $stat_real . "\n" .
> raw_line($count, 0);
> +				}
> +				WARN("VSPRINTF_POINTER_EXTENSION",
> +				     "Invalid vsprintf pointer extension
> '$bad_extension'\n" . "$here\n$stat_real\n");
> +			}
> +		}
> +
>  # Check for misused memsets
>  		if ($^V && $^V ge 5.10.0 &&
>  		    defined $stat &&
> --
> 2.10.0.rc2.1.g053435c

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#1589894 — Re: [PATCH] checkpatch: Add ability to find bad uses of vsprintf %p<foo> extensions

On Tue, 2017-02-28 at 16:06 -0800, Andrew Morton wrote:
> On Mon, 27 Feb 2017 12:54:55 -0800 Joe Perches <joe@perches.com> wrote:
> 
> > %pK was at least once misused at %pk in an out-of-tree module.
> > This lead to some security concerns.  Add the ability to track
> > single and multiple line statements for misuses of %p<foo>.
> 
> Should we also do this?
> 
> --- a/lib/vsprintf.c~checkpatch-add-ability-to-find-bad-uses-of-vsprintf-%pfoo-extensions-fix
> +++ a/lib/vsprintf.c
> @@ -1477,6 +1477,9 @@ int kptr_restrict __read_mostly;
>   * by an extra set of alphanumeric characters that are extended format
>   * specifiers.
>   *
> + * Please update scripts/checkpatch.pl when adding new conversion characters.
> + * (search for "check for vsprintf extension").
> + *

Seems sensible, thanks.

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#1589898 — Re: [kernel-hardening] Re: [PATCH] checkpatch: Add ability to find bad uses of vsprintf %p<foo> extensions

On Tue, Feb 28, 2017 at 4:06 PM, Andrew Morton
<akpm@linux-foundation.org> wrote:
> On Mon, 27 Feb 2017 12:54:55 -0800 Joe Perches <joe@perches.com> wrote:
>
>> %pK was at least once misused at %pk in an out-of-tree module.
>> This lead to some security concerns.  Add the ability to track
>> single and multiple line statements for misuses of %p<foo>.
>
> Should we also do this?

Ah yes, good idea. Maybe "...when adding/removing new conversion..." ?

-Kees

>
> --- a/lib/vsprintf.c~checkpatch-add-ability-to-find-bad-uses-of-vsprintf-%pfoo-extensions-fix
> +++ a/lib/vsprintf.c
> @@ -1477,6 +1477,9 @@ int kptr_restrict __read_mostly;
>   * by an extra set of alphanumeric characters that are extended format
>   * specifiers.
>   *
> + * Please update scripts/checkpatch.pl when adding new conversion characters.
> + * (search for "check for vsprintf extension").
> + *
>   * Right now we handle:
>   *
>   * - 'F' For symbolic function descriptor pointers with offset
> _
>



-- 
Kees Cook
Pixel Security

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#1589927 — Re: [kernel-hardening] Re: [PATCH] checkpatch: Add ability to find bad uses of vsprintf %p<foo> extensions

On Tue, 2017-02-28 at 16:11 -0800, Kees Cook wrote:
> On Tue, Feb 28, 2017 at 4:06 PM, Andrew Morton
> <akpm@linux-foundation.org> wrote:
> > On Mon, 27 Feb 2017 12:54:55 -0800 Joe Perches <joe@perches.com> wrote:
> > 
> > > %pK was at least once misused at %pk in an out-of-tree module.
> > > This lead to some security concerns.  Add the ability to track
> > > single and multiple line statements for misuses of %p<foo>.
> > 
> > Should we also do this?
> 
> Ah yes, good idea. Maybe "...when adding/removing new conversion..." ?

Deleting conversions seems unlikely.

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#1589941 — Re: [PATCH] checkpatch: Add ability to find bad uses of vsprintf %p<foo> extensions

On Mon, 27 Feb 2017 12:54:55 -0800 Joe Perches <joe@perches.com> wrote:

> %pK was at least once misused at %pk in an out-of-tree module.
> This lead to some security concerns.  Add the ability to track
> single and multiple line statements for misuses of %p<foo>.

Should we also do this?

--- a/lib/vsprintf.c~checkpatch-add-ability-to-find-bad-uses-of-vsprintf-%pfoo-extensions-fix
+++ a/lib/vsprintf.c
@@ -1477,6 +1477,9 @@ int kptr_restrict __read_mostly;
  * by an extra set of alphanumeric characters that are extended format
  * specifiers.
  *
+ * Please update scripts/checkpatch.pl when adding new conversion characters.
+ * (search for "check for vsprintf extension").
+ *
  * Right now we handle:
  *
  * - 'F' For symbolic function descriptor pointers with offset
_

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