Commit 5245dafe authored Oct 22, 2021 by Andrii Nakryiko Committed by Alexei Starovoitov Oct 22, 2021

libbpf: Fix overflow in BTF sanity checks



btf_header's str_off+str_len or type_off+type_len can overflow as they
are u32s. This will lead to bypassing the sanity checks during BTF
parsing, resulting in crashes afterwards. Fix by using 64-bit signed
integers for comparison.

Fixes: d8123624 ("libbpf: Fix BTF data layout checks and allow empty BTF")
Reported-by: Evgeny Vereshchagin <evvers@ya.ru>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211023003157.726961-1-andrii@kernel.org

parent 1c508843

tools/lib/bpf/btf.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -241,12 +241,12 @@ static int btf_parse_hdr(struct btf *btf)
		}

		meta_left = btf->raw_size - sizeof(*hdr);
		if (meta_left < hdr->str_off + hdr->str_len) {
		if (meta_left < (long long)hdr->str_off + hdr->str_len) {
		pr_debug("Invalid BTF total size:%u\n", btf->raw_size);
		return -EINVAL;
		}

		if (hdr->type_off + hdr->type_len > hdr->str_off) {
		if ((long long)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;