linux-kernel - [PATCH v7 2/4] perf symbol-elf: Ensure dso__put in machine__process_ksymbol

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Date: Mon,  6 May 2024 11:01:02 -0700
From: Ian Rogers <irogers@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Mark Rutland <mark.rutland@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, 
	Kan Liang <kan.liang@...ux.intel.com>, Athira Rajeev <atrajeev@...ux.vnet.ibm.com>, 
	Changbin Du <changbin.du@...wei.com>, Tiezhu Yang <yangtiezhu@...ngson.cn>, 
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v7 2/4] perf symbol-elf: Ensure dso__put in machine__process_ksymbol_register

dso__put after the map creation causes a use after put in the
dso__set_loaded. To ensure there is a +1 reference count on both sides
of the if-else, do a dso__get on the found map's dso.

Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/perf/util/machine.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 0b8fb14f5ff6..a3ff2ab154bd 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -683,7 +683,7 @@ static int machine__process_ksymbol_register(struct machine *machine,
 					     struct perf_sample *sample __maybe_unused)
 {
 	struct symbol *sym;
-	struct dso *dso;
+	struct dso *dso = NULL;
 	struct map *map = maps__find(machine__kernel_maps(machine), event->ksymbol.addr);
 	int err = 0;
 
@@ -696,7 +696,6 @@ static int machine__process_ksymbol_register(struct machine *machine,
 		}
 		dso__set_kernel(dso, DSO_SPACE__KERNEL);
 		map = map__new2(0, dso);
-		dso__put(dso);
 		if (!map) {
 			err = -ENOMEM;
 			goto out;
@@ -722,7 +721,7 @@ static int machine__process_ksymbol_register(struct machine *machine,
 			dso__set_long_name(dso, "", false);
 		}
 	} else {
-		dso = map__dso(map);
+		dso = dso__get(map__dso(map));
 	}
 
 	sym = symbol__new(map__map_ip(map, map__start(map)),
@@ -735,6 +734,7 @@ static int machine__process_ksymbol_register(struct machine *machine,
 	dso__insert_symbol(dso, sym);
 out:
 	map__put(map);
+	dso__put(dso);
 	return err;
 }
 
-- 
2.45.0.rc1.225.g2a3ae87e7f-goog