Re: [PATCH v7] perf test: Skip shebang and SPDX comments in shell test descriptions

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] Off-by-one error in readlink bounds check rejects exactly-fitting paths
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commit 9089c17859338d0541d199d5b734699b5eaf5d78
Author: Ian Rogers <irogers@google.com>

perf test: Skip shebang and SPDX comments in shell test descriptions

This commit refactors the shell test description extraction to correctly
skip shebang and SPDX license lines. It uses io__getline instead of
manual character reading and adds a few bounds checking adjustments.

> diff --git a/tools/perf/tests/tests-scripts.c b/tools/perf/tests/tests-scripts.c
> index f18c4cd337c8f..ec24a1d974ae0 100644
> --- a/tools/perf/tests/tests-scripts.c
> +++ b/tools/perf/tests/tests-scripts.c

[ ... ]

> @@ -178,9 +190,9 @@ static void append_script(int dir_fd, const char *name, char *desc,
>  	char *exclusive;
>  
>  	snprintf(link, sizeof(link), "/proc/%d/fd/%d", getpid(), dir_fd);
> -	len = readlink(link, filename, sizeof(filename));
> -	if (len < 0) {
> -		pr_err("Failed to readlink %s", link);
> +	len = readlink(link, filename, sizeof(filename) - 1);
> +	if (len < 0 || (size_t)len >= sizeof(filename) - strlen(name) - 2) {

[Severity: Low]
Does this bounds check erroneously reject paths that perfectly fit in the
buffer?

If len is exactly sizeof(filename) - strlen(name) - 2, the string appended
will occupy up to the last index of the buffer: filename[len] gets '/', and
strcpy() writes strlen(name) + 1 bytes starting at len + 1.

The highest index accessed is exactly sizeof(filename) - 1, which is the
very last byte of the filename array. This perfectly fits within the buffer,
yet the >= operator incorrectly triggers the error path for strings of this
exact length.

> +		pr_err("Failed to readlink %s or path too long", link);
>  		return;
>  	}
>  	filename[len++] = '/';

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Sashiko AI review · https://sashiko.dev/#/patchset/20260602073132.2653307-13-irogers@google.com?part=1