[PATCH AUTOSEL 5.4 016/175] libbpf: Fix memory leak and possible double-free in hashmap__clear

[Sasha Levin]

From: Andrii Nakryiko <andriin@xxxxxx>

[ Upstream commit 229bf8bf4d910510bc1a2fd0b89bd467cd71050d ]

Fix memory leak in hashmap_clear() not freeing hashmap_entry structs for each
of the remaining entries. Also NULL-out bucket list to prevent possible
double-free between hashmap__clear() and hashmap__free().

Running test_progs-asan flavor clearly showed this problem.

Reported-by: Alston Tang <alston64@xxxxxx>
Signed-off-by: Andrii Nakryiko <andriin@xxxxxx>
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20200429012111.277390-5-andriin@xxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 tools/lib/bpf/hashmap.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/tools/lib/bpf/hashmap.c b/tools/lib/bpf/hashmap.c
index 6122272943e6..9ef9f6201d8b 100644
--- a/tools/lib/bpf/hashmap.c
+++ b/tools/lib/bpf/hashmap.c
@@ -56,7 +56,14 @@ struct hashmap *hashmap__new(hashmap_hash_fn hash_fn,
 
 void hashmap__clear(struct hashmap *map)
 {
+	struct hashmap_entry *cur, *tmp;
+	int bkt;
+
+	hashmap__for_each_entry_safe(map, cur, tmp, bkt) {
+		free(cur);
+	}
 	free(map->buckets);
+	map->buckets = NULL;
 	map->cap = map->cap_bits = map->sz = 0;
 }
 
-- 
2.25.1