[PATCH bpf 3/3] libbpf: deal with section with no data gracefully

[Shung-Hsi Yu <shung-hsi.yu@suse.com>]

ELF section data pointer returned by libelf may be NULL (if section has
SHT_NOBITS), so null check section data pointer before attempting to
copy license and kversion section.

Fixes: cb1e5e961991 ("bpf tools: Collect version and license from ELF sections")
Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
 tools/lib/bpf/libbpf.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index c700489239e8..89f46d0616f9 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1415,6 +1415,10 @@ static int bpf_object__check_endianness(struct bpf_object *obj)
 static int
 bpf_object__init_license(struct bpf_object *obj, void *data, size_t size)
 {
+	if (!data) {
+		pr_warn("invalid license section in %s\n", obj->path);
+		return -LIBBPF_ERRNO__FORMAT;
+	}
 	/* libbpf_strlcpy() only copies first N - 1 bytes, so size + 1 won't
 	 * go over allowed ELF data section buffer
 	 */
@@ -1428,7 +1432,7 @@ bpf_object__init_kversion(struct bpf_object *obj, void *data, size_t size)
 {
 	__u32 kver;

-	if (size != sizeof(kver)) {
+	if (!data || size != sizeof(kver)) {
 		pr_warn("invalid kver section in %s\n", obj->path);
 		return -LIBBPF_ERRNO__FORMAT;
 	}
--
2.37.3