[RFC PATCH v3 04/14] libbpf: Fix memory leak and possible double-free in hashmap__clear

Ian Rogers
2020-05-08T05:38:00Z

From: Andrii Nakryiko <andriin@fb.com>

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@fb.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200429012111.277390-5-andriin@fb.com
Signed-off-by: Ian Rogers <irogers@google.com>
---
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 54c30c802070..cffb96202e0d 100644
--- a/tools/lib/bpf/hashmap.c
+++ b/tools/lib/bpf/hashmap.c
@@ -59,7 +59,14 @@ 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;
}

--
2.26.2.645.ge9eca65c58-goog