bpf: don't set id on after map lookup with ptr_to_map_val return

In the verifier there is no such semantics where registers with
PTR_TO_MAP_VALUE type have an id assigned to them. This is only
used in PTR_TO_MAP_VALUE_OR_NULL and later on nullified once the
test against NULL has been pattern matched and type transformed
into PTR_TO_MAP_VALUE.

Fixes: 3e6a4b3e0289 ("bpf/verifier: introduce BPF_PTR_TO_MAP_VALUE")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Roman Gushchin <guro@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 6 insertions, 5 deletions

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 774fa40a32ae..1971ca325fb4 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2852,10 +2852,6 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn
                 regs[BPF_REG_0].type = NOT_INIT;
         } else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL ||
                    fn->ret_type == RET_PTR_TO_MAP_VALUE) {
-                if (fn->ret_type == RET_PTR_TO_MAP_VALUE)
-                        regs[BPF_REG_0].type = PTR_TO_MAP_VALUE;
-                else
-                        regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL;
                 /* There is no offset yet applied, variable or fixed */
                 mark_reg_known_zero(env, regs, BPF_REG_0);
                 /* remember map_ptr, so that check_map_access()
@@ -2868,7 +2864,12 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn
                         return -EINVAL;
                 }
                 regs[BPF_REG_0].map_ptr = meta.map_ptr;
-                regs[BPF_REG_0].id = ++env->id_gen;
+                if (fn->ret_type == RET_PTR_TO_MAP_VALUE) {
+                        regs[BPF_REG_0].type = PTR_TO_MAP_VALUE;
+                } else {
+                        regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL;
+                        regs[BPF_REG_0].id = ++env->id_gen;
+                }
         } else if (fn->ret_type == RET_PTR_TO_SOCKET_OR_NULL) {
                 int id = acquire_reference_state(env, insn_idx);
                 if (id < 0)