[PATCH 5.13 100/300] libbpf: Fix removal of inner map in bpf_object__create_map

Greg Kroah-Hartman
2021-09-13T14:00:07Z

From: Martynas Pumputis <m@lambda.lt>

[ Upstream commit a21ab4c59e09c2a9994a6e393b7484e3b3f78a99 ]

If creating an outer map of a BTF-defined map-in-map fails (via
bpf_object__create_map()), then the previously created its inner map
won't be destroyed.

Fix this by ensuring that the destroy routines are not bypassed in the
case of a failure.

Fixes: 646f02ffdd49c ("libbpf: Add BTF-defined map-in-map support")
Reported-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Martynas Pumputis <m@lambda.lt>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210719173838.423148-2-m@lambda.lt
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/lib/bpf/libbpf.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 2af2d0e4a231..f6ebda75b030 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -4409,6 +4409,7 @@ static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map)
{
struct bpf_create_map_attr create_attr;
struct bpf_map_def *def = &map->def;
+ int err = 0;

memset(&create_attr, 0, sizeof(create_attr));

@@ -4451,8 +4452,6 @@ static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map)

if (bpf_map_type__is_map_in_map(def->type)) {
if (map->inner_map) {
- int err;
-
err = bpf_object__create_map(obj, map->inner_map);
if (err) {
pr_warn("map '%s': failed to create inner map: %d\n",
@@ -4469,8 +4468,8 @@ static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map)
if (map->fd < 0 && (create_attr.btf_key_type_id ||
create_attr.btf_value_type_id)) {
char *cp, errmsg[STRERR_BUFSIZE];
- int err = -errno;

+ err = -errno;
cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
pr_warn("Error in bpf_create_map_xattr(%s):%s(%d). Retrying without BTF.\n",
map->name, cp, err);
@@ -4482,15 +4481,14 @@ static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map)
map->fd = bpf_create_map_xattr(&create_attr);
}

- if (map->fd < 0)
- return -errno;
+ err = map->fd < 0 ? -errno : 0;

if (bpf_map_type__is_map_in_map(def->type) && map->inner_map) {
bpf_map__destroy(map->inner_map);
zfree(&map->inner_map);
}

- return 0;
+ return err;
}

static int init_map_slots(struct bpf_map *map)
--
2.30.2