bpf: Extract nullable reg type conversion into a helper function

mainline inclusion
from mainline-v5.12-rc1
commit 4ddb7416
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5EUVD
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=4ddb74165ae580b6dcbb5ab1919d994fc8d03c3f

--------------------------------

Extract conversion from a register's nullable type to a type with a
value. The helper will be used in mark_ptr_not_null_reg().
Signed-off-by: NDmitrii Banshchikov <me@ubique.spb.ru>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210212205642.620788-3-me@ubique.spb.ru

Conflicts:
	kernel/bpf/verifier.c
Signed-off-by: NWang Yufen <wangyufen@huawei.com>

kernel/bpf/verifier.c

@@ -1081,6 +1081,28 @@ static void mark_reg_known_zero(struct bpf_verifier_env *env,
 	__mark_reg_known_zero(regs + regno);
 }
 
+static void mark_ptr_not_null_reg(struct bpf_reg_state *reg)
+{
+	if (base_type(reg->type) == PTR_TO_MAP_VALUE) {
+		const struct bpf_map *map = reg->map_ptr;
+
+		if (map->inner_map_meta) {
+			reg->type = CONST_PTR_TO_MAP;
+			reg->map_ptr = map->inner_map_meta;
+		} else if (map->map_type == BPF_MAP_TYPE_XSKMAP) {
+			reg->type = PTR_TO_XDP_SOCK;
+		} else if (map->map_type == BPF_MAP_TYPE_SOCKMAP ||
+			   map->map_type == BPF_MAP_TYPE_SOCKHASH) {
+			reg->type = PTR_TO_SOCKET;
+		} else {
+			reg->type = PTR_TO_MAP_VALUE;
+		}
+		return;
+	}
+
+	reg->type &= ~PTR_MAYBE_NULL;
+}
+
 static bool reg_is_pkt_pointer(const struct bpf_reg_state *reg)
 {
 	return type_is_pkt_pointer(reg->type);
@@ -7849,32 +7871,19 @@ static void mark_ptr_or_null_reg(struct bpf_func_state *state,
 		}
 		if (is_null) {
 			reg->type = SCALAR_VALUE;
-		} else if (base_type(reg->type) == PTR_TO_MAP_VALUE) {
-			const struct bpf_map *map = reg->map_ptr;
-
-			if (map->inner_map_meta) {
-				reg->type = CONST_PTR_TO_MAP;
-				reg->map_ptr = map->inner_map_meta;
-			} else if (map->map_type == BPF_MAP_TYPE_XSKMAP) {
-				reg->type = PTR_TO_XDP_SOCK;
-			} else if (map->map_type == BPF_MAP_TYPE_SOCKMAP ||
-				   map->map_type == BPF_MAP_TYPE_SOCKHASH) {
-				reg->type = PTR_TO_SOCKET;
-			} else {
-				reg->type = PTR_TO_MAP_VALUE;
-			}
-		} else {
-			reg->type &= ~PTR_MAYBE_NULL;
-		}
-
-		if (is_null) {
 			/* We don't need id and ref_obj_id from this point
 			 * onwards anymore, thus we should better reset it,
 			 * so that state pruning has chances to take effect.
 			 */
 			reg->id = 0;
 			reg->ref_obj_id = 0;
-		} else if (!reg_may_point_to_spin_lock(reg)) {
+
+			return;
+		}
+
+		mark_ptr_not_null_reg(reg);
+
+		if (!reg_may_point_to_spin_lock(reg)) {
 			/* For not-NULL ptr, reg->ref_obj_id will be reset
 			 * in release_reg_references().
 			 *