From 37c3e92657ffcb4bfdb3bdaedf52cf8cc0da99fa Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Tue, 23 Nov 2021 16:23:16 -0800 Subject: [PATCH] libbpf: Don't call libc APIs with NULL pointers Sanitizer complains about qsort(), bsearch(), and memcpy() being called with NULL pointer. This can only happen when the associated number of elements is zero, so no harm should be done. But still prevent this from happening to keep sanitizer runs clean from extra noise. Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20211124002325.1737739-5-andrii@kernel.org --- src/libbpf.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/src/libbpf.c b/src/libbpf.c index 2806b2f..cec23ed 100644 --- a/src/libbpf.c +++ b/src/libbpf.c @@ -3369,7 +3369,8 @@ static int bpf_object__elf_collect(struct bpf_object *obj) /* sort BPF programs by section name and in-section instruction offset * for faster search */ - qsort(obj->programs, obj->nr_programs, sizeof(*obj->programs), cmp_progs); + if (obj->nr_programs) + qsort(obj->programs, obj->nr_programs, sizeof(*obj->programs), cmp_progs); return bpf_object__init_btf(obj, btf_data, btf_ext_data); } @@ -5823,6 +5824,8 @@ static int cmp_relo_by_insn_idx(const void *key, const void *elem) static struct reloc_desc *find_prog_insn_relo(const struct bpf_program *prog, size_t insn_idx) { + if (!prog->nr_reloc) + return NULL; return bsearch(&insn_idx, prog->reloc_desc, prog->nr_reloc, sizeof(*prog->reloc_desc), cmp_relo_by_insn_idx); } @@ -5838,8 +5841,9 @@ static int append_subprog_relos(struct bpf_program *main_prog, struct bpf_progra relos = libbpf_reallocarray(main_prog->reloc_desc, new_cnt, sizeof(*relos)); if (!relos) return -ENOMEM; - memcpy(relos + main_prog->nr_reloc, subprog->reloc_desc, - sizeof(*relos) * subprog->nr_reloc); + if (subprog->nr_reloc) + memcpy(relos + main_prog->nr_reloc, subprog->reloc_desc, + sizeof(*relos) * subprog->nr_reloc); for (i = main_prog->nr_reloc; i < new_cnt; i++) relos[i].insn_idx += subprog->sub_insn_off;