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

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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: Song Liu <songliubraving@fb.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200729232148.896125-1-andriin@fb.com
This commit is contained in:
Andrii Nakryiko 2020-07-29 16:21:48 -07:00 committed by Daniel Borkmann
parent a6599abdea
commit 50450fc716
3 changed files with 7 additions and 8 deletions
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4
tools/lib/bpf/btf.c
View File

@ -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);

2
tools/lib/bpf/btf_dump.c
View File

@ -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);

9
tools/lib/bpf/libbpf.c
View File

@ -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++) {
@ -9379,8 +9379,7 @@ 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);
bpf_link__destroy(*link);
*link = NULL;
}
}