Merge branch 'fix-for-check_func_arg_reg_off'

Kumar Kartikeya Dwivedi says:

====================
Fix for check_func_arg_reg_off

Remove a leftover hunk in check_func_arg_reg_off that incorrectly
bypasses reg->off == 0 requirement for release kfuncs and helpers.
====================

Link: https://lore.kernel.org/r/20230822175140.1317749-1-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Author: Alexei Starovoitov

kernel/bpf/verifier.c

@@ -7973,17 +7973,6 @@ int check_func_arg_reg_off(struct bpf_verifier_env *env,
 		if (arg_type_is_dynptr(arg_type) && type == PTR_TO_STACK)
 			return 0;
 
-		if ((type_is_ptr_alloc_obj(type) || type_is_non_owning_ref(type)) && reg->off) {
-			if (reg_find_field_offset(reg, reg->off, BPF_GRAPH_NODE_OR_ROOT))
-				return __check_ptr_off_reg(env, reg, regno, true);
-
-			verbose(env, "R%d must have zero offset when passed to release func\n",
-				regno);
-			verbose(env, "No graph node or root found at R%d type:%s off:%d\n", regno,
-				btf_type_name(reg->btf, reg->btf_id), reg->off);
-			return -EINVAL;
-		}
-
 		/* Doing check_ptr_off_reg check for the offset will catch this
 		 * because fixed_off_ok is false, but checking here allows us
 		 * to give the user a better error message.

tools/testing/selftests/bpf/progs/local_kptr_stash_fail.c

@@ -62,4 +62,24 @@ long stash_rb_nodes(void *ctx)
 	return 0;
 }
 
+SEC("tc")
+__failure __msg("R1 must have zero offset when passed to release func")
+long drop_rb_node_off(void *ctx)
+{
+	struct map_value *mapval;
+	struct node_data *res;
+	int idx = 0;
+
+	mapval = bpf_map_lookup_elem(&some_nodes, &idx);
+	if (!mapval)
+		return 1;
+
+	res = bpf_obj_new(typeof(*res));
+	if (!res)
+		return 1;
+	/* Try releasing with graph node offset */
+	bpf_obj_drop(&res->node);
+	return 0;
+}
+
 char _license[] SEC("license") = "GPL";