linux-kernel - Re: [PATCH v1] perf pmu: Avoid segv for missing name/alias

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Message-ID: <aDYnLedM8RT17FHx@x1>
Date: Tue, 27 May 2025 17:57:17 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: Namhyung Kim <namhyung@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>, Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Kan Liang <kan.liang@...ux.intel.com>,
	James Clark <james.clark@...aro.org>,
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] perf pmu: Avoid segv for missing name/alias_name in
 wildcarding

On Tue, May 27, 2025 at 01:33:35PM -0700, Ian Rogers wrote:
> On Fri, Apr 4, 2025 at 11:07 AM Namhyung Kim <namhyung@...nel.org> wrote:
> > On Wed, Apr 02, 2025 at 02:13:01PM -0700, Ian Rogers wrote:
> > > The pmu name or alias_name fields may be NULL and should be skipped if
> > > so. This is done in all loops of perf_pmu___name_match except the
> > > final wildcard loop which was an oversight.

> > > Fixes: c786468a3585 ("perf pmu: Rename name matching for no suffix or wildcard variants")
> > > Signed-off-by: Ian Rogers <irogers@...gle.com>

> > Acked-by: Namhyung Kim <namhyung@...nel.org>
 
> Ping.

⬢ [acme@...lbx perf-tools-next]$ patch -p1 < ./20250402_irogers_perf_pmu_avoid_segv_for_missing_name_alias_name_in_wildcarding.mbx
patching file tools/perf/util/pmu.c
Hunk #1 FAILED at 2060.
1 out of 1 hunk FAILED -- saving rejects to file tools/perf/util/pmu.c.rej
⬢ [acme@...lbx perf-tools-next]$ 

⬢ [acme@...lbx perf-tools-next]$ cat tools/perf/util/pmu.c.rej
--- tools/perf/util/pmu.c
+++ tools/perf/util/pmu.c
@@ -2060,7 +2060,9 @@ static bool perf_pmu___name_match(const struct perf_pmu *pmu, const char *to_mat
 	}
 	for (size_t i = 0; i < ARRAY_SIZE(names); i++) {
 		const char *name = names[i];
-		
+
+		if (!name)
+			continue;
 		if (wildcard && perf_pmu__match_wildcard_uncore(name, to_match))
 			return true;
 		if (!wildcard && perf_pmu__match_ignoring_suffix_uncore(name, to_match))
⬢ [acme@...lbx perf-tools-next]$

⬢ [acme@...lbx perf-tools-next]$ git log --oneline -5 tools/perf/util/pmu.c
754baf426e099fbf perf pmu: Change aliases from list to hashmap
255f5b6d060be5a4 perf parse-events: Add "cpu" term to set the CPU an event is recorded on
fa1332a8011eebe1 perf mem/c2c amd: Add ldlat support
fc807b6bde6ad332 perf pmu-events: Add retirement latency to JSON events inside of perf
58b8b5d142a8bd5c perf cpumap: Increment reference count for online cpumap
⬢ [acme@...lbx perf-tools-next]$ 

Can you please take a look?

- Arnaldo