From: Andrii Nakryiko andriin@fb.com
[ Upstream commit 3415ec643e7bd644b03026efbe2f2b36cbe9b34b ]
5d01ab7bac46 ("libbpf: fix erroneous multi-closing of BTF FD") introduced backwards-compatibility issue, manifesting itself as -E2BIG error returned on program load due to unknown non-zero btf_fd attribute value for BPF_PROG_LOAD sys_bpf() sub-command.
This patch fixes bug by ensuring that we only ever associate BTF FD with program if there is a BTF.ext data that was successfully loaded into kernel, which automatically means kernel supports func_info/line_info and associated BTF FD for progs (checked and ensured also by BTF sanitization code).
Fixes: 5d01ab7bac46 ("libbpf: fix erroneous multi-closing of BTF FD") Reported-by: Andrey Ignatov rdna@fb.com Signed-off-by: Andrii Nakryiko andriin@fb.com Signed-off-by: Alexei Starovoitov ast@kernel.org 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 e308fcf16cdd0..ce579e3654d60 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -2066,7 +2066,11 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt, load_attr.license = license; load_attr.kern_version = kern_version; load_attr.prog_ifindex = prog->prog_ifindex; - btf_fd = bpf_object__btf_fd(prog->obj); + /* if .BTF.ext was loaded, kernel supports associated BTF for prog */ + if (prog->obj->btf_ext) + btf_fd = bpf_object__btf_fd(prog->obj); + else + btf_fd = -1; load_attr.prog_btf_fd = btf_fd >= 0 ? btf_fd : 0; load_attr.func_info = prog->func_info; load_attr.func_info_rec_size = prog->func_info_rec_size;