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, `$1` can be initialized to the text that capture group matches thereby setting it to the desired and required value. Reviewed-by: Lukas Bulwahn Tested-by: Lukas Bulwahn Signed-off-by: Mrinal Pandey --- Changes since v1: Add Reviewed-by and Tested-by tag scripts/checkpatch.pl | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index 4c820607540b..e73e998d582a 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -2636,8 +2636,8 @@ sub process { # Check if the commit log has what seems like a diff which can confuse patch if ($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