When there are no program sections, obj->programs is left unallocated,
and find_prog_by_sec_insn()'s search lands on &obj->programs[0] == NULL,
and will cause null-pointer dereference in the following access to
prog->sec_idx.
Guard the search with obj->nr_programs similar to what's being done in
__bpf_program__iter() to prevent null-pointer access from happening.
Fixes: db2b8b06423c ("libbpf: Support CO-RE relocations for multi-prog sections")
Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@xxxxxxxx>
---
tools/lib/bpf/libbpf.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index a64e13c654f3..c700489239e8 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -4112,6 +4112,9 @@ static struct bpf_program *find_prog_by_sec_insn(const struct bpf_object *obj,
int l = 0, r = obj->nr_programs - 1, m;
struct bpf_program *prog;
+ if (!obj->nr_programs)
+ return NULL;
+
while (l < r) {
m = l + (r - l + 1) / 2;
prog = &obj->programs[m];
--
2.37.3
