On 4/1/24 11:16 PM, Philo Lu wrote:
Taking different maps within a single bpf_for_each_map_elem call is not
allowed before, because from the second map,
bpf_insn_aux_data->map_ptr_state will be marked as *poison*. In fact
both map_ptr and state are needed to support this use case: map_ptr is
used by set_map_elem_callback_state() while poison state is needed to
determine whether to use direct call.
Signed-off-by: Philo Lu <lulie@xxxxxxxxxxxxxxxxx>
---
kernel/bpf/verifier.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 515ac6165ab1..f0a33f7c2604 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -9649,11 +9649,7 @@ static int set_map_elem_callback_state(struct bpf_verifier_env *env,
struct bpf_map *map;
int err;
- if (bpf_map_ptr_poisoned(insn_aux)) {
- verbose(env, "tail_call abusing map_ptr\n");
- return -EINVAL;
- }
-
+ /* should not check poison */
Maybe change comments to below?
/* valid map_ptr and poison value does not matter */
map = insn_aux->map_ptr_state.map_ptr;
if (!map->ops->map_set_for_each_callback_args ||
!map->ops->map_for_each_callback) {
