Re: [PATCH v2 1/4] perf config: Move perf_config__set_variable() to util/config.c

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] perf: strcmp crash on OOM via perf_etc_perfconfig()
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commit fa97c6103dec622e75b990c48525b0269551b0aa
Author: Arnaldo Carvalho de Melo <acme@redhat.com>

perf config: Move perf_config__set_variable() to util/config.c

This commit moves perf_config__set_variable() out of the perf config builtin
so that opt-in features can persist their choice from outside it. It also
serializes parsing and rewriting of config files using a mutex to support
concurrent access from multiple threads.

> diff --git a/tools/perf/util/config.c b/tools/perf/util/config.c
> --- a/tools/perf/util/config.c
> +++ b/tools/perf/util/config.c
[ ... ]
> +int perf_config__set_variable(const char *var, const char *value)
> +{
> +	char path[PATH_MAX];
> +	char *user_config = mkpath(path, sizeof(path), "%s/.perfconfig", getenv("HOME"));
> +	const char *config_filename = config_exclusive_filename ?: user_config;
> +		/*
> +	 * When rewriting the system wide file all entries are marked as coming
> +	 * from it and must be kept, or it would be truncated down to its
> +	 * header.
> +	 */
> +	bool system_config = strcmp(config_filename, perf_etc_perfconfig()) == 0;

[Severity: Medium]
Can this cause a segmentation fault under memory pressure?

In perf_config__set_variable(), if ETC_PERFCONFIG is an absolute path and
system_path() fails to allocate memory via strdup(), it returns NULL. 

This NULL propagates through perf_etc_perfconfig() and is passed directly
as the second argument to strcmp(), which will crash when dereferencing it.

[ ... ]

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Sashiko AI review · https://sashiko.dev/#/patchset/20260928171244.2437283-1-acme@kernel.org?part=1