[PATCH 6.1 0212/1146] libbpf: Deal with section with no data gracefully

Greg Kroah-Hartman
2022-12-28T15:25:43Z

From: Shung-Hsi Yu <shung-hsi.yu@suse.com>

[ Upstream commit 35a855509e6ee3442477c8ebc6827b5b5d32a7b5 ]

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>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20221012022353.7350-3-shung-hsi.yu@suse.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 b7fac0df2612..a0d3cc39ea73 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1408,6 +1408,10 @@ 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
*/
@@ -1421,7 +1425,7 @@ 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;
}
--
2.35.1