libbpf: Add NULL check to add_dummy_ksym_var

Avoids a segv if btf isn't present. Seen on the call path
__bpf_object__open calling bpf_object__collect_externs.

Fixes: 5bd022ec01 (libbpf: Support extern kernel function)
Suggested-by: Stanislav Fomichev <sdf@google.com>
Suggested-by: Petar Penkov <ppenkov@google.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210504234910.976501-1-irogers@google.com
This commit is contained in:
Ian Rogers 2021-05-04 16:49:10 -07:00 committed by Andrii Nakryiko
parent 1682d8df20
commit 9683e5775c
1 changed files with 3 additions and 0 deletions

View File

@ -3216,6 +3216,9 @@ static int add_dummy_ksym_var(struct btf *btf)
const struct btf_var_secinfo *vs;
const struct btf_type *sec;
if (!btf)
return 0;
sec_btf_id = btf__find_by_name_kind(btf, KSYMS_SEC,
BTF_KIND_DATASEC);
if (sec_btf_id < 0)