Currently we cannot pass the pointer returned by iter next method as
argument to KF_TRUSTED_ARGS kfuncs, because the pointer returned by
iter next method is not "valid".
This patch sets the pointer returned by iter next method to be valid.
This is based on the fact that if the iterator is implemented correctly,
then the pointer returned from the iter next method should be valid.
This does not make NULL pointer valid. If the iter next method has
KF_RET_NULL flag, then the verifier will ask the ebpf program to
check NULL pointer.
Signed-off-by: Juntong Deng <juntong.deng@xxxxxxxxxxx>
---
kernel/bpf/verifier.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index ebec74c28ae3..35a7b7c6679c 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -12832,6 +12832,10 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
/* For mark_ptr_or_null_reg, see 93c230e3f5bd6 */
regs[BPF_REG_0].id = ++env->id_gen;
}
+
+ if (is_iter_next_kfunc(&meta))
+ regs[BPF_REG_0].type |= PTR_TRUSTED;
+
mark_btf_func_reg_size(env, BPF_REG_0, sizeof(void *));
if (is_kfunc_acquire(&meta)) {
int id = acquire_reference_state(env, insn_idx);
--
2.39.2
