perf mmap: Fix NULL deref in aio cleanup on alloc failure

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:claude-opus-4.6
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
index 4404a99eee45f9c3d2a9942464fb7f97720898e1..d64aec6c7c843e815ea96e3eda4b4db88c8534e6 100644 (file)
--- 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]));
 }