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Date:   Thu, 30 May 2019 19:04:34 -0700
From:   Kees Cook <keescook@chromium.org>
To:     Matteo Croce <mcroce@redhat.com>
Cc:     linux-kernel@vger.kernel.org, Andy Whitcroft <apw@canonical.com>,
        Joe Perches <joe@perches.com>,
        Aaron Tomlin <atomlin@redhat.com>,
        Matthew Wilcox <willy@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v2] checkpatch.pl: Warn on duplicate sysctl local variable
Message-ID: <201905301904.D8D90210@keescook>
References: <20190531011227.21181-1-mcroce@redhat.com>
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On Fri, May 31, 2019 at 03:12:27AM +0200, Matteo Croce wrote:
> Commit 6a33853c5773 ("proc/sysctl: add shared variables for range check")
> adds some shared const variables to be used instead of a local copy in
> each source file.
> Warn when a chunk duplicates one of these values in a ctl_table struct:
> 
>     $ scripts/checkpatch.pl 0001-test-commit.patch
>     WARNING: duplicated sysctl range checking value 'zero', consider using the shared one in include/linux/sysctl.h
>     #27: FILE: arch/arm/kernel/isa.c:48:
>     +               .extra1         = &zero,
> 
>     WARNING: duplicated sysctl range checking value 'int_max', consider using the shared one in include/linux/sysctl.h
>     #28: FILE: arch/arm/kernel/isa.c:49:
>     +               .extra2         = &int_max,
> 
>     total: 0 errors, 2 warnings, 14 lines checked
> 
> Signed-off-by: Matteo Croce <mcroce@redhat.com>

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

-Kees

> ---
>  scripts/checkpatch.pl | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index 342c7c781ba5..629c31435487 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -6639,6 +6639,12 @@ sub process {
>  				     "unknown module license " . $extracted_string . "\n" . $herecurr);
>  			}
>  		}
> +
> +# check for sysctl duplicate constants
> +		if ($line =~ /\.extra[12]\s*=\s*&(zero|one|int_max|max_int)\b/) {
> +			WARN("DUPLICATED_SYSCTL_CONST",
> +				"duplicated sysctl range checking value '$1', consider using the shared one in include/linux/sysctl.h\n" . $herecurr);
> +		}
>  	}
>  
>  	# If we have no input at all, then there is nothing to report on
> -- 
> 2.21.0
> 

-- 
Kees Cook