[PATCH 1/2] perf: do not call zfree() on uninitialized pointer

["Jiri Slaby (SUSE)" <jirislaby@kernel.org>]

In add_drm_pmu(), the check for type > PERF_PMU_TYPE_DRM_END happens
before "drm" is allocated by zalloc(). The error path nevertheless
called zfree(&drm), i.e. free() on an uninitialized pointer, which
can crash. Remove this bogus zfree() -- nothing has been allocated
yet at this point, so there is nothing to free.

Fixes this compiler warning:
In function ‘__zfree’,
    inlined from ‘add_drm_pmu’ at util/drm_pmu.c:110:3,
    inlined from ‘read_drm_pmus_cb’ at util/drm_pmu.c:174:10:
../lib/zalloc.c:13:9: warning: ‘drm’ may be used uninitialized [-Wmaybe-uninitialized]
   13 |         free(*ptr);
      |         ^

Assisted-by: LLM
Fixes: 28917cb17f9d ("perf drm_pmu: Add a tool like PMU to expose DRM information")
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Cc: Ian Rogers <irogers@google.com>
---
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: James Clark <james.clark@linaro.org>
Cc: linux-perf-users@vger.kernel.org
---
 tools/perf/util/drm_pmu.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/tools/perf/util/drm_pmu.c b/tools/perf/util/drm_pmu.c
index b8badae7015c..5e4bdd8e7fa8 100644
--- a/tools/perf/util/drm_pmu.c
+++ b/tools/perf/util/drm_pmu.c
@@ -107,7 +107,6 @@ static struct drm_pmu *add_drm_pmu(struct list_head *pmus, char *line, size_t li
 		type = PERF_PMU_TYPE_DRM_START;
 
 	if (type > PERF_PMU_TYPE_DRM_END) {
-		zfree(&drm);
 		pr_err("Unable to encode DRM PMU type for %s\n", name);
 		return NULL;
 	}
-- 
2.56.0