ipe_bdev_setintegrity() frees the old root hash when dm-verity publishes
a new one on ->preresume, while policy evaluation can still be
dereferencing it.
Protect the root hash with RCU. The evaluation path already runs under
rcu_read_lock().
Fixes: e155858dd9 ("ipe: add support for dm-verity as a trust provider")
Cc: stable@vger.kernel.org
Assisted-by: LLM
[FW: remove model name according to latest guideline]
Signed-off-by: Fan Wu <wufan@kernel.org>