Commit ed9cc6b6 authored Jul 03, 2024 by Andreas Ziegler Committed by Greg Kroah-Hartman Sep 12, 2024

libbpf: Add NULL checks to bpf_object__{prev_map,next_map}



[ 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.com


Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 77ab0fd2

tools/lib/bpf/libbpf.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -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;