From: Ian Rogers <irogers@google.com>
Date: Tue, 4 May 2021 23:49:10 +0000 (-0700)
Subject: libbpf: Add NULL check to add_dummy_ksym_var
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=9683e5775c75097c46bd24e65411b16ac6c6cbb3;p=linux.git

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: 5bd022ec01f0 (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
---

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index e2a3cf4378140..c41d9b2b59ace 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -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)