Commit 50450fc7 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Daniel Borkmann
Browse files

libbpf: Make destructors more robust by handling ERR_PTR(err) cases 



Most of libbpf "constructors" on failure return ERR_PTR(err) result encoded as
a pointer. It's a common mistake to eventually pass such malformed pointers
into xxx__destroy()/xxx__free() "destructors". So instead of fixing up
clean up code in selftests and user programs, handle such error pointers in
destructors themselves. This works beautifully for NULL pointers passed to
destructors, so might as well just work for error pointers.

Suggested-by: default avatarSong Liu <songliubraving@fb.com>
Signed-off-by: default avatarAndrii Nakryiko <andriin@fb.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarSong Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200729232148.896125-1-andriin@fb.com
parent a6599abd

tools/lib/bpf/btf.c

+2 −2
Original line number Diff line number Diff line
@@ -386,7 +386,7 @@ __s32 btf__find_by_name_kind(const struct btf *btf, const char *type_name, 


void btf__free(struct btf *btf)

{

	if (!btf)

	if (IS_ERR_OR_NULL(btf))

		return;



	if (btf->fd >= 0)
@@ -1025,7 +1025,7 @@ static int btf_ext_parse_hdr(__u8 *data, __u32 data_size) 


void btf_ext__free(struct btf_ext *btf_ext)

{

	if (!btf_ext)

	if (IS_ERR_OR_NULL(btf_ext))

		return;

	free(btf_ext->data);

	free(btf_ext);

tools/lib/bpf/btf_dump.c

+1 −1
Original line number Diff line number Diff line
@@ -183,7 +183,7 @@ void btf_dump__free(struct btf_dump *d) 
{

	int i, cnt;



	if (!d)

	if (IS_ERR_OR_NULL(d))

		return;



	free(d->type_states);

tools/lib/bpf/libbpf.c

+4 −5
Original line number Diff line number Diff line
@@ -6504,7 +6504,7 @@ void bpf_object__close(struct bpf_object *obj) 
{

	size_t i;



	if (!obj)

	if (IS_ERR_OR_NULL(obj))

		return;



	if (obj->clear_priv)
@@ -7690,7 +7690,7 @@ int bpf_link__destroy(struct bpf_link *link) 
{

	int err = 0;



	if (!link)

	if (IS_ERR_OR_NULL(link))

		return 0;



	if (!link->disconnected && link->detach)
@@ -8502,7 +8502,7 @@ void perf_buffer__free(struct perf_buffer *pb) 
{

	int i;



	if (!pb)

	if (IS_ERR_OR_NULL(pb))

		return;

	if (pb->cpu_bufs) {

		for (i = 0; i < pb->cpu_cnt; i++) {
@@ -9379,7 +9379,6 @@ void bpf_object__detach_skeleton(struct bpf_object_skeleton *s) 
	for (i = 0; i < s->prog_cnt; i++) {

		struct bpf_link **link = s->progs[i].link;



		if (!IS_ERR_OR_NULL(*link))

		bpf_link__destroy(*link);

		*link = NULL;

	}

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