[PATCH bpf-next v3 2/5] bpf: Check acquire_reference() error for "__ref" struct_ops arguments

[Amery Hung <ameryhung@gmail.com>]

When acquiring references for struct_ops program arguments tagged with
"__ref", the return value of acquire_reference() was stored directly
into u32 ctx_arg_info[i].ref_id without checking for failure.
acquire_reference() returns -ENOMEM when acquire_reference_state() fails
to allocate, so the error was silently stored as a ref_id instead of
aborting verification. Fix it by checking the return.

Fixes: a687df2008f6 ("bpf: Support getting referenced kptr from struct_ops argument")
Signed-off-by: Amery Hung <ameryhung@gmail.com>
---
 kernel/bpf/verifier.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 6446db9628ae..80a72402463d 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -18362,9 +18362,13 @@ static int do_check_common(struct bpf_verifier_env *env, int subprog)
 
 	/* Acquire references for struct_ops program arguments tagged with "__ref" */
 	if (!subprog && env->prog->type == BPF_PROG_TYPE_STRUCT_OPS) {
-		for (i = 0; i < aux->ctx_arg_info_size; i++)
-			aux->ctx_arg_info[i].ref_id = aux->ctx_arg_info[i].refcounted ?
-						      acquire_reference(env, 0, 0) : 0;
+		for (i = 0; i < aux->ctx_arg_info_size; i++) {
+			ret = aux->ctx_arg_info[i].refcounted ? acquire_reference(env, 0, 0) : 0;
+			if (ret < 0)
+				goto out;
+
+			aux->ctx_arg_info[i].ref_id = ret;
+		}
 	}
 
 	ret = do_check(env);
-- 
2.53.0-Meta