[PATCH bpf-next] bpf: Disallow bpf_obj_new_impl call when bpf_mem_alloc_init fails

[Kumar Kartikeya Dwivedi <memxor@gmail.com>]

In the unlikely event that bpf_global_ma is not correctly initialized,
instead of checking the boolean everytime bpf_obj_new_impl is called,
simply check it while loading the program and return an error if
bpf_global_ma_set is false.

Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
 kernel/bpf/helpers.c  | 2 --
 kernel/bpf/verifier.c | 6 ++++++
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 89a95f3d854c..3d4edd314450 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -1760,8 +1760,6 @@ void *bpf_obj_new_impl(u64 local_type_id__k, void *meta__ign)
 	u64 size = local_type_id__k;
 	void *p;

-	if (unlikely(!bpf_global_ma_set))
-		return NULL;
 	p = bpf_mem_alloc(&bpf_global_ma, size);
 	if (!p)
 		return NULL;
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 5bc9d84d7924..ea36107deee0 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -8878,6 +8878,12 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
 				struct btf *ret_btf;
 				u32 ret_btf_id;

+				/* Unlikely, but fail the kfunc call if bpf_global_ma
+				 * is not initialized.
+				 */
+				if (!bpf_global_ma_set)
+					return -ENOMEM;
+
 				if (((u64)(u32)meta.arg_constant.value) != meta.arg_constant.value) {
 					verbose(env, "local type ID argument must be in range [0, U32_MAX]\n");
 					return -EINVAL;
--
2.38.1