libbpf: Fix null-pointer dereference in find_prog_by_sec_insn()
authorShung-Hsi Yu <shung-hsi.yu@suse.com>
Wed, 12 Oct 2022 02:23:53 +0000 (10:23 +0800)
committerAndrii Nakryiko <andrii@kernel.org>
Thu, 13 Oct 2022 17:53:34 +0000 (10:53 -0700)
commitd0d382f95a9270dcf803539d6781d6bd67e3f5b2
treef42662b1b505ba76f5f4e635ebd6d003295c8342
parent35a855509e6ee3442477c8ebc6827b5b5d32a7b5
libbpf: Fix null-pointer dereference in find_prog_by_sec_insn()

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@suse.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20221012022353.7350-4-shung-hsi.yu@suse.com
tools/lib/bpf/libbpf.c