[PATCH 04/11] perf tools: NULL bitmap pointers after bitmap_free()

[Arnaldo Carvalho de Melo]

From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>

Two call sites free bitmaps without NULLing the pointer, risking
double-free if the structure is reused or cleanup is called twice:

 - mmap__munmap():                 map->affinity_mask.bits
 - record__mmap_cpu_mask_free():   mask->bits

Set each pointer to NULL after bitmap_free().

Fixes: 8384a2600c7ddfc8 ("perf record: Adapt affinity to machines with #CPUs > 1K")
Fixes: f466e5ed6c356d1d ("perf record: Extend --threads command line option")
Reported-by: sashiko-bot <sashiko-bot@xxxxxxxxxx>
Reviewed-by: Ian Rogers <irogers@xxxxxxxxxx>
Cc: Alexey Budankov <alexey.budankov@xxxxxxxxxxxxxxx>
Cc: Alexey Bayduraev <alexey.v.bayduraev@xxxxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Assisted-by: Claude Opus 4.6 <noreply@xxxxxxxxxxxxx>
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/builtin-record.c | 1 +
 tools/perf/util/mmap.c      | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index a33c78f030d91012..e915390556752b9e 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -3084,6 +3084,7 @@ static int record__mmap_cpu_mask_alloc(struct mmap_cpu_mask *mask, int nr_bits)
 static void record__mmap_cpu_mask_free(struct mmap_cpu_mask *mask)
 {
 	bitmap_free(mask->bits);
+	mask->bits = NULL;
 	mask->nbits = 0;
 }
 
diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
index d64aec6c7c843e81..358e70c4f3edd077 100644
--- a/tools/perf/util/mmap.c
+++ b/tools/perf/util/mmap.c
@@ -238,6 +238,8 @@ static void perf_mmap__aio_munmap(struct mmap *map __maybe_unused)
 void mmap__munmap(struct mmap *map)
 {
 	bitmap_free(map->affinity_mask.bits);
+	map->affinity_mask.bits = NULL;
+	map->affinity_mask.nbits = 0;
 
 	zstd_fini(&map->zstd_data);
 
-- 
2.54.0