On 1/9/21 11:03 PM, Andrii Nakryiko wrote:
Empty BTFs do come up (e.g., simple kernel modules with no new types and
strings, compared to the vmlinux BTF) and there is nothing technically wrong
with them. So remove unnecessary check preventing loading empty BTFs.
Reported-by: Christopher William Snowhill <chris@xxxxxxxxxx>
Fixes: ("d8123624506c libbpf: Fix BTF data layout checks and allow empty BTF")
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
---
tools/lib/bpf/btf.c | 5 -----
1 file changed, 5 deletions(-)
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 3c3f2bc6c652..9970a288dda5 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -240,11 +240,6 @@ static int btf_parse_hdr(struct btf *btf)
}
meta_left = btf->raw_size - sizeof(*hdr);
- if (!meta_left) {
- pr_debug("BTF has no data\n");
- return -EINVAL;
- }
Previous kernel patch allows empty btf only if that btf is module (not
base/vmlinux) btf. Here it seems we allow any empty non-module btf to be
loaded into the kernel. In such cases, loading may fail? Maybe we should
detect such cases in libbpf and error out instead of going to kernel and
get error back?
-
if (meta_left < hdr->str_off + hdr->str_len) {
pr_debug("Invalid BTF total size:%u\n", btf->raw_size);
return -EINVAL;
