[PATCH bpf 1/2] libbpf: fix removal of inner map in bpf_object__create_map

From: Martynas Pumputis <m@lambda.lt>
To: bpf@vger.kernel.org
Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, m@lambda.lt
Subject: [PATCH bpf 1/2] libbpf: fix removal of inner map in bpf_object__create_map
Date: Wed, 14 Jul 2021 18:54:39 +0200	[thread overview]
Message-ID: <20210714165440.472566-2-m@lambda.lt> (raw)
In-Reply-To: <20210714165440.472566-1-m@lambda.lt>

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>
---
 tools/lib/bpf/libbpf.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 6f5e2757bb3c..1a840e81ea0a 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -4479,6 +4479,7 @@ static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map, b
 {
 	struct bpf_create_map_attr create_attr;
 	struct bpf_map_def *def = &map->def;
+	int ret = 0;
 
 	memset(&create_attr, 0, sizeof(create_attr));
 
@@ -4561,7 +4562,7 @@ static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map, b
 	}
 
 	if (map->fd < 0)
-		return -errno;
+		ret = -errno;
 
 	if (bpf_map_type__is_map_in_map(def->type) && map->inner_map) {
 		if (obj->gen_loader)
@@ -4570,7 +4571,7 @@ static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map, b
 		zfree(&map->inner_map);
 	}
 
-	return 0;
+	return ret;
 }
 
 static int init_map_slots(struct bpf_object *obj, struct bpf_map *map)
-- 
2.32.0

