bpf: Fix inner map state pruning regression.

Introduction of map_uid made two lookups from outer map to be distinct.
That distinction is only necessary when inner map has an embedded timer.
Otherwise it will make the verifier state pruning to be conservative
which will cause complex programs to hit 1M insn_processed limit.
Tighten map_uid logic to apply to inner maps with timers only.

Fixes: 6d640d971c86 ("bpf: Prevent pointer mismatch in bpf_timer_init.")
Reported-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Lorenz Bauer <lmb@cloudflare.com>
Link: https://lore.kernel.org/bpf/CACAyw99hVEJFoiBH_ZGyy=+oO-jyydoz6v1DeKPKs2HVsUH28w@mail.gmail.com
Link: https://lore.kernel.org/bpf/20211110172556.20754-1-alexei.starovoitov@gmail.com

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 890b3ec375a394a862799cc5b07718d571d19a4d..aab7482ed1c3840daafeb27fb709ff36ab4f95f8 100644 (file)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1151,7 +1151,8 @@ static void mark_ptr_not_null_reg(struct bpf_reg_state *reg)
                        /* transfer reg's id which is unique for every map_lookup_elem
                         * as UID of the inner map.
                         */
-                       reg->map_uid = reg->id;
+                       if (map_value_has_timer(map->inner_map_meta))
+                               reg->map_uid = reg->id;
                } else if (map->map_type == BPF_MAP_TYPE_XSKMAP) {
                        reg->type = PTR_TO_XDP_SOCK;
                } else if (map->map_type == BPF_MAP_TYPE_SOCKMAP ||