perf machine: Fix refcount usage when processing PERF_RECORD_KSYMBOL

ASan reported a memory leak of BPF-related ksymbols map and dso. The
leak is caused by refount never reaching 0, due to missing __put calls
in the function machine__process_ksymbol_register.

Once the dso is inserted in the map, dso__put() should be called
(map__new2() increases the refcount to 2).

The same thing applies for the map when it's inserted into maps
(maps__insert() increases the refcount to 2).

  $ sudo ./perf record -- sleep 5
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.025 MB perf.data (8 samples) ]

  =================================================================
  ==297735==ERROR: LeakSanitizer: detected memory leaks

  Direct leak of 6992 byte(s) in 19 object(s) allocated from:
      #0 0x4f43c7 in calloc (/home/user/linux/tools/perf/perf+0x4f43c7)
      #1 0x8e4e53 in map__new2 /home/user/linux/tools/perf/util/map.c:216:20
      #2 0x8cf68c in machine__process_ksymbol_register /home/user/linux/tools/perf/util/machine.c:778:10
      [...]

  Indirect leak of 8702 byte(s) in 19 object(s) allocated from:
      #0 0x4f43c7 in calloc (/home/user/linux/tools/perf/perf+0x4f43c7)
      #1 0x8728d7 in dso__new_id /home/user/linux/tools/perf/util/dso.c:1256:20
      #2 0x872015 in dso__new /home/user/linux/tools/perf/util/dso.c:1295:9
      #3 0x8cf623 in machine__process_ksymbol_register /home/user/linux/tools/perf/util/machine.c:774:21
      [...]

  Indirect leak of 1520 byte(s) in 19 object(s) allocated from:
      #0 0x4f43c7 in calloc (/home/user/linux/tools/perf/perf+0x4f43c7)
      #1 0x87b3da in symbol__new /home/user/linux/tools/perf/util/symbol.c:269:23
      #2 0x888954 in map__process_kallsym_symbol /home/user/linux/tools/perf/util/symbol.c:710:8
      [...]

  Indirect leak of 1406 byte(s) in 19 object(s) allocated from:
      #0 0x4f43c7 in calloc (/home/user/linux/tools/perf/perf+0x4f43c7)
      #1 0x87b3da in symbol__new /home/user/linux/tools/perf/util/symbol.c:269:23
      #2 0x8cfbd8 in machine__process_ksymbol_register /home/user/linux/tools/perf/util/machine.c:803:8
      [...]

Signed-off-by: Riccardo Mancini <rickyman7@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tommi Rantala <tommi.t.rantala@nokia.com>
Link: http://lore.kernel.org/lkml/20210612173751.188582-1-rickyman7@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 3ff4936a15a4..da19be7da284 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -776,10 +776,10 @@ static int machine__process_ksymbol_register(struct machine *machine,
 		if (dso) {
 			dso->kernel = DSO_SPACE__KERNEL;
 			map = map__new2(0, dso);
+			dso__put(dso);
 		}
 
 		if (!dso || !map) {
-			dso__put(dso);
 			return -ENOMEM;
 		}
 
@@ -792,6 +792,7 @@ static int machine__process_ksymbol_register(struct machine *machine,
 		map->start = event->ksymbol.addr;
 		map->end = map->start + event->ksymbol.len;
 		maps__insert(&machine->kmaps, map);
+		map__put(map);
 		dso__set_loaded(dso);
 
 		if (is_bpf_image(event->ksymbol.name)) {