Re: [PATCH v1 16/26] perf pmu: Use generic hashmap for pmu aliases

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found no new issues
in this patch, but noticed 1 related pre-existing issue it does not
introduce:
- [Medium] perf pmu: memory leak of alias on error paths in
  perf_pmu__new_alias() [1]
--

commit 728d5dacfc35f09b0b16561c8cccc0e78616532f
Author: Ian Rogers <irogers@google.com>

perf pmu: Use generic hashmap for pmu aliases

This commit converts perf_pmu::aliases to use a typed generic hashmap
declared with DECLARE_HASHMAP(pmu_aliases_map, ...) and updates alias
iterations to use hashmap__for_each().

> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index a63fa0d9cfa59..cabc14260719d 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c

[ ... ]

> @@ -676,7 +676,7 @@ static int perf_pmu__new_alias(struct perf_pmu *pmu, const char *name,
>  		break;
>  
>  	}
> -	hashmap__set(pmu->aliases, alias->name, alias, /*old_key=*/ NULL, &old_alias);
> +	hashmap__set(pmu->aliases, alias->name, alias, /*old_key=*/NULL, &old_alias);
>  	perf_pmu_free_alias(old_alias);
>  	return 0;
>  }

[Severity: Medium]
This problem wasn't introduced by this patch, but can perf_pmu__new_alias()
leak alias on its earlier error paths [1]?

tools/perf/util/pmu.c:perf_pmu__new_alias() {
	...
	alias = zalloc(sizeof(*alias));
	if (!alias)
		return -ENOMEM;
	...
	if (!ret && pe && pe->retirement_latency_max) {
		ret = parse_double(pe->retirement_latency_max, NULL,
				   &alias->retirement_latency_max);
	}
	if (ret)
		return ret;

	if (val_fd < 0) {
		alias->terms = strdup(val);
	} else {
		...
		ret = io__getline(&io, &alias->terms, &line_len) < 0 ? -errno : 0;
		if (ret) {
			pr_err("Failed to read alias %s\n", name);
			return ret;
		}
	...
}

If parse_double() fails on any of the retirement latency fields or
io__getline() fails when reading the sysfs alias terms, the function
returns ret directly without freeing alias.

[1] https://sashiko.dev/#/bug/linux-11ab1439-acca-4a2e-9366-3dcd430baf6e

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261113214850.3329699-1-irogers@google.com?part=16