Re: [PATCH v2] checkpatch: Fix the usage of capture group ( ... )

[Lukas Bulwahn <lukas.bulwahn@gmail.com>]

On Tue, 14 Jul 2020, Mrinal Pandey wrote:

> The usage of "capture group (...)" in the immediate condition after `&&`
> results in `$1` being uninitialized. This issues a warning "Use of
> uninitialized value $1 in regexp compilation at ./scripts/checkpatch.pl
> line 2638".
> 
> I noticed this bug while running checkpatch on the set of commits from
> v5.7 to v5.8-rc1 of the kernel on the commits with a diff content in
> their commit message.
> 
> This bug was introduced in the script by commit e518e9a59ec3
> ("checkpatch: emit an error when there's a diff in a changelog"). It has
> been in the script since then.
> 
> The author intended to store the match made by capture group in variable
> `$1`. This should have contained the name of the file as `[\w/]+` matched.
> However, this couldn't be accomplished due to usage of capture group and
> `$1` in the same regular expression.
> 
> Fix this by placing the capture group in the condition before `&&`.
> Thus, `$1` can be initialized to the text that capture group matches
> thereby setting it to the desired and required value.
> 
> Reviewed-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
> Tested-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
> Signed-off-by: Mrinal Pandey <mrinalmni@gmail.com>
> ---
> Changes since v1:
> Add Reviewed-by and Tested-by tag
>

Hi Joe,

did you see this quick fix to checkpatch.pl? Can you comment on the 
commit and can we get a quick ack on that fix, please?

General question on patches for ./scripts/checkpatch.pl:

How do they travel to Linus?

Do you pick those patches and provide them to Andrew Morton?
Or do you just ack them and we need to send them to Andrew Morton to get 
them into mainline?

(get_maintainers tells us to just send those patches to you and Andy.)


Lukas


>  scripts/checkpatch.pl | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index 4c820607540b..e73e998d582a 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -2636,8 +2636,8 @@ sub process {
>  
>  # Check if the commit log has what seems like a diff which can confuse patch
>  		if ($in_commit_log && !$commit_log_has_diff &&
> -		    (($line =~ m@^\s+diff\b.*a/[\w/]+@ &&
> -		      $line =~ m@^\s+diff\b.*a/([\w/]+)\s+b/$1\b@) ||
> +		    (($line =~ m@^\s+diff\b.*a/([\w/]+)@ &&
> +		      $line =~ m@^\s+diff\b.*a/[\w/]+\s+b/$1\b@) ||
>  		     $line =~ m@^\s*(?:\-\-\-\s+a/|\+\+\+\s+b/)@ ||
>  		     $line =~ m/^\s*\@\@ \-\d+,\d+ \+\d+,\d+ \@\@/)) {
>  			ERROR("DIFF_IN_COMMIT_MSG",
> -- 
> 2.25.1
> 
>