Re: [PATCH 04/12] perf debuginfo: Let the user skip and disable debuginfod fetches

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] perf: Thread-unsafe setenv() during concurrent execution risks crashes
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commit f05833c6d0f3f46ab299b21fc5d5d3a85ee8249e
Author: Arnaldo Carvalho de Melo <acme@redhat.com>

perf debuginfo: Let the user skip and disable debuginfod fetches

This commit introduces interactivity during debuginfod fetches, allowing the
user to press 's' to skip the current fetch or 'd' to cancel it and disable
debuginfod for the rest of the session. The terminal is placed in raw mode
to intercept these keys.

> diff --git a/tools/perf/util/debuginfo.c b/tools/perf/util/debuginfo.c
> index be5882d9c2204..e2066fce2450c 100644
> --- a/tools/perf/util/debuginfo.c
> +++ b/tools/perf/util/debuginfo.c
[ ... ]
> +static void debuginfod__cancel_key(int key)
> +{
> +	if (key == 's' || key == 'S') {
> +		debuginfod_fetch_cancelled = true;
> +		debuginfod__skipped("Skipping this debuginfod fetch, this build ID will not be fetched again in this session, press 'd' to also disable it for the other ones");
> +	} else if (key == 'd' || key == 'D') {
> +		debuginfod_fetch_cancelled = true;
> +		symbol_conf.debuginfod = false;
> +		/*
> +		 * libdwfl's own debuginfod client reads DEBUGINFOD_URLS
> +		 * in every query, so clear it to stop it as well.
> +		 */
> +		setenv("DEBUGINFOD_URLS", "", 1);

[Severity: Medium]
Is it safe to call setenv() here? Modifying the global environment can
reallocate the environ array or free existing environment strings.

If another thread in a multithreaded tool like perf top concurrently calls
getenv() (either explicitly, or implicitly via libc functions like localtime
or gettext), could it read from a freed pointer, resulting in a use-after-free
or crash?

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Sashiko AI review · https://sashiko.dev/#/patchset/20260916114740.48230-1-acme@kernel.org?part=4