libbpf: Fix BTF data layout checks and allow empty BTF (d8123624) · Commits · 戴 / test

Make data section layout checks stricter, disallowing overlap of types and strings data. Additionally, allow BTFs with no type data. There is nothing inherently wrong with having BTF with no types (put potentially with some strings). This could be a situation with kernel module BTFs, if module doesn't introduce any new type information. Also fix invalid offset alignment check for btf->hdr->type_off. Fixes: ("bpf: btf: Add BTF support to libbpf") Signed-off-by:

Andrii Nakryiko <andrii@kernel.org> Signed-off-by:

Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20201105043402.2530976-8-andrii@kernel.org

tools/lib/bpf/btf.c

+6 −10

Original line number	Diff line number	Diff line
		@@ -245,22 +245,18 @@ static int btf_parse_hdr(struct btf *btf)
		return -EINVAL;
		}

		if (meta_left < hdr->type_off) {
		pr_debug("Invalid BTF type section offset:%u\n", hdr->type_off);
		if (meta_left < hdr->str_off + hdr->str_len) {
		pr_debug("Invalid BTF total size:%u\n", btf->raw_size);
		return -EINVAL;
		}

		if (meta_left < hdr->str_off) {
		pr_debug("Invalid BTF string section offset:%u\n", hdr->str_off);
		if (hdr->type_off + hdr->type_len > hdr->str_off) {
		pr_debug("Invalid BTF data sections layout: type data at %u + %u, strings data at %u + %u\n",
		hdr->type_off, hdr->type_len, hdr->str_off, hdr->str_len);
		return -EINVAL;
		}

		if (hdr->type_off >= hdr->str_off) {
		pr_debug("BTF type section offset >= string section offset. No type?\n");
		return -EINVAL;
		}

		if (hdr->type_off & 0x02) {
		if (hdr->type_off % 4) {
		pr_debug("BTF type section is not aligned to 4 bytes\n");
		return -EINVAL;
		}

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