linux-kernel - [PATCH v2] perf session: check for null pointer before derefernce

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Message-Id: <20220125121141.18347-1-amhamza.mgc@gmail.com>
Date:   Tue, 25 Jan 2022 17:11:41 +0500
From:   Ameer Hamza <amhamza.mgc@...il.com>
To:     mark.rutland@....com, alexander.shishkin@...ux.intel.com,
        jolsa@...hat.com, namhyung@...nel.org
Cc:     peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
        rickyman7@...il.com, alexey.v.bayduraev@...ux.intel.com,
        adrian.hunter@...el.com, leo.yan@...aro.org, german.gomez@....com,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        amhamza.mgc@...il.com, James Clark <james.clark@....com>
Subject: [PATCH v2] perf session: check for null pointer before derefernce

Move null pointer check before dereferncing the variable

Addresses-Coverity: 1497622 ("Derereference before null check")

Reviewed-by: James Clark <james.clark@....com>

Signed-off-by: Ameer Hamza <amhamza.mgc@...il.com>

---
v1 -> v2: It should be possible to dump stuff if machine is NULL.
---
 tools/perf/util/session.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index f19348dddd55..210eeee3dd70 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1503,11 +1503,12 @@ static int machines__deliver_event(struct machines *machines,
 			++evlist->stats.nr_unknown_id;
 			return 0;
 		}
-		dump_sample(evsel, event, sample, perf_env__arch(machine->env));
 		if (machine == NULL) {
 			++evlist->stats.nr_unprocessable_samples;
+			dump_sample(evsel, event, sample, perf_env__arch(NULL));
 			return 0;
 		}
+		dump_sample(evsel, event, sample, perf_env__arch(machine->env));
 		return evlist__deliver_sample(evlist, tool, event, sample, evsel, machine);
 	case PERF_RECORD_MMAP:
 		return tool->mmap(tool, event, sample, machine);
-- 
2.25.1