[PATCH AUTOSEL 5.9 040/111] libbpf: Close map fd if init map slots failed

Sasha Levin
2020-10-18T19:59:00Z

From: Hangbin Liu <liuhangbin@gmail.com>

[ Upstream commit a0f2b7acb4b1d29127ff99c714233b973afd1411 ]

Previously we forgot to close the map fd if bpf_map_update_elem()
failed during map slot init, which will leak map fd.

Let's move map slot initialization to new function init_map_slots() to
simplify the code. And close the map fd if init slot failed.

Reported-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20201006021345.3817033-2-liuhangbin@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/lib/bpf/libbpf.c | 55 ++++++++++++++++++++++++++----------------
1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index e493d6048143f..d71d93c56363c 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -3841,6 +3841,36 @@ static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map)
return 0;
}

+static int init_map_slots(struct bpf_map *map)
+{
+ const struct bpf_map *targ_map;
+ unsigned int i;
+ int fd, err;
+
+ for (i = 0; i < map->init_slots_sz; i++) {
+ if (!map->init_slots[i])
+ continue;
+
+ targ_map = map->init_slots[i];
+ fd = bpf_map__fd(targ_map);
+ err = bpf_map_update_elem(map->fd, &i, &fd, 0);
+ if (err) {
+ err = -errno;
+ pr_warn("map '%s': failed to initialize slot [%d] to map '%s' fd=%d: %d\n",
+ map->name, i, targ_map->name,
+ fd, err);
+ return err;
+ }
+ pr_debug("map '%s': slot [%d] set to map '%s' fd=%d\n",
+ map->name, i, targ_map->name, fd);
+ }
+
+ zfree(&map->init_slots);
+ map->init_slots_sz = 0;
+
+ return 0;
+}
+
static int
bpf_object__create_maps(struct bpf_object *obj)
{
@@ -3883,28 +3913,11 @@ bpf_object__create_maps(struct bpf_object *obj)
}

if (map->init_slots_sz) {
- for (j = 0; j < map->init_slots_sz; j++) {
- const struct bpf_map *targ_map;
- int fd;
-
- if (!map->init_slots[j])
- continue;
-
- targ_map = map->init_slots[j];
- fd = bpf_map__fd(targ_map);
- err = bpf_map_update_elem(map->fd, &j, &fd, 0);
- if (err) {
- err = -errno;
- pr_warn("map '%s': failed to initialize slot [%d] to map '%s' fd=%d: %d\n",
- map->name, j, targ_map->name,
- fd, err);
- goto err_out;
- }
- pr_debug("map '%s': slot [%d] set to map '%s' fd=%d\n",
- map->name, j, targ_map->name, fd);
+ err = init_map_slots(map);
+ if (err < 0) {
+ zclose(map->fd);
+ goto err_out;
}
- zfree(&map->init_slots);
- map->init_slots_sz = 0;
}

if (map->pin_path && !map->pinned) {
--
2.25.1