linux-kernel - Re: [PATCH v2] perf pmu: Avoid segv for missing name/alias

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Message-ID: <aDcFF35JF4002MfK@x1>
Date: Wed, 28 May 2025 09:44:07 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
	Namhyung Kim <namhyung@...nel.org>,
	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 v2] perf pmu: Avoid segv for missing name/alias_name in
 wildcarding

On Tue, May 27, 2025 at 02:50:35PM -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")

I fixed the Fixes: to the right commit, as it seems to have been rebased
and ended up not present on my local repo:

Fixes: 63e287131cf0c59b ("perf pmu: Rename name matching for no suffix or wildcard variants")

⬢ [acme@...lbx perf-tools-next]$ git tag --contains 63e287131cf0c59b | grep ^v6
v6.15
v6.15-rc1
v6.15-rc2
v6.15-rc3
v6.15-rc4
v6.15-rc5
v6.15-rc6
v6.15-rc7
⬢ [acme@...lbx perf-tools-next]$

Or something else:

⬢ [acme@...lbx perf-tools-next]$ git tag --contains 86468a358 | grep ^v6
error: malformed object name 86468a358
⬢ [acme@...lbx perf-tools-next]$ git cat-file -t c786468a3585
fatal: Not a valid object name c786468a3585
⬢ [acme@...lbx perf-tools-next]$ 

further details:

commit 63e287131cf0c59b026053d6d63fe271604ffa7e
Author: Ian Rogers <irogers@...gle.com>
Date:   Fri Jan 31 23:43:18 2025 -0800

    perf pmu: Rename name matching for no suffix or wildcard variants
    
    Wildcard PMU naming will match a name like pmu_1 to a PMU name like
    pmu_10 but not to a PMU name like pmu_2 as the suffix forms part of
    the match. No suffix matching will match pmu_10 to either pmu_1 or
    pmu_2. Add or rename matching functions on PMU to make it clearer what
    kind of matching is being performed.
    
    Signed-off-by: Ian Rogers <irogers@...gle.com>
    Reviewed-by: Kan Liang <kan.liang@...ux.intel.com>
    Link: https://lore.kernel.org/r/20250201074320.746259-4-irogers@google.com
    Signed-off-by: Namhyung Kim <namhyung@...nel.org>

Thanks, applied.

- Arnaldo

> Signed-off-by: Ian Rogers <irogers@...gle.com>
> Acked-by: Namhyung Kim <namhyung@...nel.org>
> ---
> v2. Rebase resolving merge conflicts, add Namhyung's Acked-by.
> ---
>  tools/perf/util/pmu.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index bc1178234d3b..609828513f6c 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c
> @@ -2143,6 +2143,9 @@ 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))
> -- 
> 2.49.0.1204.g71687c7c1d-goog
>