[PATCH v1] perf pmu: Avoid uninitialized use of alias->str

[Ian Rogers]

alias is allocated with malloc allowing uninitialized memory to be
accessed. The initialization of str was moved late after it could have
been updated by a JSON event, however, this create a potential for an
uninitialized use. Fix this by assigning str to NULL early. Testing on
ARM (Raspberry Pi) showed a memory leak in the same code so add a
zfree.

Fixes: f63a536f03a2 ("perf pmu: Merge JSON events with sysfs at load time")
Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
---
 tools/perf/util/pmu.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index cde33e01959a..b3f8f3f1e900 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -532,6 +532,7 @@ static int perf_pmu__new_alias(struct perf_pmu *pmu, const char *name,
 	if (!alias)
 		return -ENOMEM;
 
+	alias->str = NULL;
 	INIT_LIST_HEAD(&alias->terms);
 	alias->scale = 1.0;
 	alias->unit[0] = '\0';
@@ -593,6 +594,7 @@ static int perf_pmu__new_alias(struct perf_pmu *pmu, const char *name,
 			ret += scnprintf(newval + ret, sizeof(newval) - ret,
 					 "%s=%s", term->config, term->val.str);
 	}
+	zfree(&alias->str);
 	alias->str = strdup(newval);
 	if (!pe)
 		pmu->sysfs_aliases++;
-- 
2.42.0.rc2.253.gd59a3bf2b4-goog