From: Andrii Nakryiko andrii@kernel.org
[ 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 andrii@kernel.org Signed-off-by: Alexei Starovoitov ast@kernel.org Link: https://lore.kernel.org/bpf/20201105043402.2530976-8-andrii@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 d606a358480da..3380aadb74655 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -100,22 +100,18 @@ 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; }