Re: [PATCH v2] kbuild: Makefile.lib: fix offsets generation with debug info

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] kbuild: unanchored sed substitutions in sed-offsets can break build
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commit 48672ceb9d59753178f125f7c16956dd57252dcd
Author: Dmitry Kandybka <d.kandybka@gmail.com>

kbuild: Makefile.lib: fix offsets generation with debug info

This commit fixes offset generation when debug information is enabled by
making the sed pattern matching stricter and adding a BLANK() macro for
readability. It prevents debug metadata from leaking into generated header
files and breaking the build.

> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
> index 19e96b30a122f..173bc3aa4247f 100644
> --- a/scripts/Makefile.lib
> +++ b/scripts/Makefile.lib
> @@ -493,9 +493,9 @@ quiet_cmd_zstd22_with_size = ZSTD22  $@
>  # the .ascii directive whereas GCC keeps the <space> as-is.
>  define sed-offsets
>  	's:^[[:space:]]*\.ascii[[:space:]]*"\(.*\)".*:\1:; \
> -	/^->/{s:->#\(.*\):/* \1 */:; \
> -	s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; \
> -	s:->::; p;}'
> +	/^->/{s:->#\(.*\):/* \1 */:p; \
> +	s:^->\([[:alnum:]_]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:p; \
> +	s:->BLANK()::p;}'

[Severity: Low]
Could this unanchored sed substitution break the build under certain
conditions?

If the kernel is built with debug info (e.g., -ggdb3), the compiler may emit
.ascii directives containing debug strings from source code. If a string
literal from an included header starts with -> and contains -># or ->BLANK()
mid-string (for example, ->foo ->BLANK()), the unanchored sed substitution
will match mid-string.

Because of the :p flag, wouldn't it print the partially modified pattern space
(e.g., ->foo ), resulting in invalid C code being written to
include/generated/asm-offsets.h?

Should the pattern be anchored (e.g., s:^->BLANK()$::p;) to ensure it only
matches the intended kbuild macros?

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Sashiko AI review · https://sashiko.dev/#/patchset/20261015210149.78470-1-d.kandybka@gmail.com?part=1