[PATCH 1/7] perf mmap: Fix NULL deref in aio cleanup on alloc failure

[Arnaldo Carvalho de Melo <acme@kernel.org>]

From: Arnaldo Carvalho de Melo <acme@redhat.com>

perf_mmap__aio_mmap() sets map->aio.nr_cblocks before allocating the
data array.  If calloc() for aiocb or cblocks fails before the data
array is allocated, the return -1 path leads to perf_mmap__aio_munmap()
which loops nr_cblocks times calling perf_mmap__aio_free().  Both
versions of perf_mmap__aio_free() (NUMA and non-NUMA) dereference
map->aio.data[idx] without checking if data is NULL, causing a NULL
pointer dereference.

Add NULL checks for map->aio.data at the top of both
perf_mmap__aio_free() variants so the cleanup path is safe when
allocation fails partway through perf_mmap__aio_mmap().

Fixes: d3d1af6f011a553a ("perf record: Enable asynchronous trace writing")
Reported-by: sashiko-bot <sashiko-bot@kernel.org>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Assisted-by: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/mmap.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
index 4404a99eee45f9c3..d64aec6c7c843e81 100644
--- a/tools/perf/util/mmap.c
+++ b/tools/perf/util/mmap.c
@@ -89,10 +89,10 @@ static int perf_mmap__aio_alloc(struct mmap *map, int idx)
 
 static void perf_mmap__aio_free(struct mmap *map, int idx)
 {
-	if (map->aio.data[idx]) {
-		munmap(map->aio.data[idx], mmap__mmap_len(map));
-		map->aio.data[idx] = NULL;
-	}
+	if (!map->aio.data || !map->aio.data[idx])
+		return;
+	munmap(map->aio.data[idx], mmap__mmap_len(map));
+	map->aio.data[idx] = NULL;
 }
 
 static int perf_mmap__aio_bind(struct mmap *map, int idx, struct perf_cpu cpu, int affinity)
@@ -141,6 +141,8 @@ static int perf_mmap__aio_alloc(struct mmap *map, int idx)
 
 static void perf_mmap__aio_free(struct mmap *map, int idx)
 {
+	if (!map->aio.data)
+		return;
 	zfree(&(map->aio.data[idx]));
 }
 
-- 
2.54.0