5.4-stable review patch. If anyone has any objections, please let me know.
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From: Andreas Ziegler ziegler.andreas@siemens.com
[ Upstream commit cedc12c5b57f7efa6dbebfb2b140e8675f5a2616 ]
In the current state, an erroneous call to bpf_object__find_map_by_name(NULL, ...) leads to a segmentation fault through the following call chain:
bpf_object__find_map_by_name(obj = NULL, ...) -> bpf_object__for_each_map(pos, obj = NULL) -> bpf_object__next_map((obj = NULL), NULL) -> return (obj = NULL)->maps
While calling bpf_object__find_map_by_name with obj = NULL is obviously incorrect, this should not lead to a segmentation fault but rather be handled gracefully.
As __bpf_map__iter already handles this situation correctly, we can delegate the check for the regular case there and only add a check in case the prev or next parameter is NULL.
Signed-off-by: Andreas Ziegler ziegler.andreas@siemens.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Link: https://lore.kernel.org/bpf/20240703083436.505124-1-ziegler.andreas@siemens.... Signed-off-by: Sasha Levin sashal@kernel.org --- tools/lib/bpf/libbpf.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index b8849812449c..98e34c517267 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -4754,7 +4754,7 @@ __bpf_map__iter(const struct bpf_map *m, const struct bpf_object *obj, int i) struct bpf_map * bpf_map__next(const struct bpf_map *prev, const struct bpf_object *obj) { - if (prev == NULL) + if (prev == NULL && obj != NULL) return obj->maps;
return __bpf_map__iter(prev, obj, 1); @@ -4763,7 +4763,7 @@ bpf_map__next(const struct bpf_map *prev, const struct bpf_object *obj) struct bpf_map * bpf_map__prev(const struct bpf_map *next, const struct bpf_object *obj) { - if (next == NULL) { + if (next == NULL && obj != NULL) { if (!obj->nr_maps) return NULL; return obj->maps + obj->nr_maps - 1;