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perf machine: Fix refcount usage when processing PERF_RECORD_KSYMBOL
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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 <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Ian Rogers <[email protected]>
Cc: Jiapeng Chong <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Tommi Rantala <[email protected]>
Link: http://lore.kernel.org/lkml/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
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Manciukic authored and acmel committed Jun 19, 2021
1 parent fe7a98b commit c087e94
Showing 1 changed file with 2 additions and 1 deletion.
3 changes: 2 additions & 1 deletion tools/perf/util/machine.c
Original file line number Diff line number Diff line change
Expand Up @@ -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;
}

Expand All @@ -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)) {
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