libbpf: Make btf__resolve_size logic always check size error condition

commit 994021a7e08477f7e51285920aac99fc967fae8a upstream.

Perform size check always in btf__resolve_size. Makes the logic a bit more
robust against corrupted BTF and silences LGTM/Coverity complaining about
always true (size < 0) check.

Fixes: 69eaab04c675 ("btf: extract BTF type size calculation")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20191107020855.3834758-5-andriin@fb.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 1aa189a..d606a35 100644 (file)
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -269,10 +269,9 @@ __s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
                t = btf__type_by_id(btf, type_id);
        }
 
+done:
        if (size < 0)
                return -EINVAL;
-
-done:
        if (nelems && size > UINT32_MAX / nelems)
                return -E2BIG;