bpf: Avoid storing modifier to info->btf_id

info->btf_id expects the btf_id of a struct, so it should
store the final result after skipping modifiers (if any).

It also takes this chanace to add a missing newline in one of the
bpf_log() messages.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200109003456.3855176-1-kafai@fb.com

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index ed20758847247c988c41cbd5610368160b22b358..497ecf62d79d0b9f4d2f802333a7cce6f68f2bf1 100644 (file)
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -3697,7 +3697,6 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type,
 
        /* this is a pointer to another type */
        info->reg_type = PTR_TO_BTF_ID;
-       info->btf_id = t->type;
 
        if (tgt_prog) {
                ret = btf_translate_to_vmlinux(log, btf, t, tgt_prog->type);
@@ -3708,10 +3707,14 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type,
                        return false;
                }
        }
+
+       info->btf_id = t->type;
        t = btf_type_by_id(btf, t->type);
        /* skip modifiers */
-       while (btf_type_is_modifier(t))
+       while (btf_type_is_modifier(t)) {
+               info->btf_id = t->type;
                t = btf_type_by_id(btf, t->type);
+       }
        if (!btf_type_is_struct(t)) {
                bpf_log(log,
                        "func '%s' arg%d type %s is not a struct\n",
@@ -3737,7 +3740,7 @@ int btf_struct_access(struct bpf_verifier_log *log,
 again:
        tname = __btf_name_by_offset(btf_vmlinux, t->name_off);
        if (!btf_type_is_struct(t)) {
-               bpf_log(log, "Type '%s' is not a struct", tname);
+               bpf_log(log, "Type '%s' is not a struct\n", tname);
                return -EINVAL;
        }