From 4d4d6aa2ef803044badb1529a1bfb45680f4071e Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Wed, 4 Nov 2020 20:33:57 -0800 Subject: [PATCH] libbpf: Fix BTF data layout checks and allow empty BTF [ Upstream commit d8123624506cd62730c9cd9c7672c698e462703d ] 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: 8a138aed4a80 ("bpf: btf: Add BTF support to libbpf") Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20201105043402.2530976-8-andrii@kernel.org Signed-off-by: Sasha Levin --- tools/lib/bpf/btf.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-) diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index 231b07203e3d..987c1515b828 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -215,22 +215,18 @@ 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; }