nvme-tcp: fix a possible UAF when failing to allocate an io queue

When we allocate a nvme-tcp queue, we set the data_ready callback before
we actually need to use it. This creates the potential that if a stray
controller sends us data on the socket before we connect, we can trigger
the io_work and start consuming the socket.

In this case reported: we failed to allocate one of the io queues, and
as we start releasing the queues that we already allocated, we get
a UAF [1] from the io_work which is running before it should really.

Fix this by setting the socket ops callbacks only before we start the
queue, so that we can't accidentally schedule the io_work in the
initialization phase before the queue started. While we are at it,
rename nvme_tcp_restore_sock_calls to pair with nvme_tcp_setup_sock_ops.

[1]:
[16802.107284] nvme nvme4: starting error recovery
[16802.109166] nvme nvme4: Reconnecting in 10 seconds...
[16812.173535] nvme nvme4: failed to connect socket: -111
[16812.173745] nvme nvme4: Failed reconnect attempt 1
[16812.173747] nvme nvme4: Reconnecting in 10 seconds...
[16822.413555] nvme nvme4: failed to connect socket: -111
[16822.413762] nvme nvme4: Failed reconnect attempt 2
[16822.413765] nvme nvme4: Reconnecting in 10 seconds...
[16832.661274] nvme nvme4: creating 32 I/O queues.
[16833.919887] BUG: kernel NULL pointer dereference, address: 0000000000000088
[16833.920068] nvme nvme4: Failed reconnect attempt 3
[16833.920094] #PF: supervisor write access in kernel mode
[16833.920261] nvme nvme4: Reconnecting in 10 seconds...
[16833.920368] #PF: error_code(0x0002) - not-present page
[16833.921086] Workqueue: nvme_tcp_wq nvme_tcp_io_work [nvme_tcp]
[16833.921191] RIP: 0010:_raw_spin_lock_bh+0x17/0x30
...
[16833.923138] Call Trace:
[16833.923271]  <TASK>
[16833.923402]  lock_sock_nested+0x1e/0x50
[16833.923545]  nvme_tcp_try_recv+0x40/0xa0 [nvme_tcp]
[16833.923685]  nvme_tcp_io_work+0x68/0xa0 [nvme_tcp]
[16833.923824]  process_one_work+0x1e8/0x390
[16833.923969]  worker_thread+0x53/0x3d0
[16833.924104]  ? process_one_work+0x390/0x390
[16833.924240]  kthread+0x124/0x150
[16833.924376]  ? set_kthread_struct+0x50/0x50
[16833.924518]  ret_from_fork+0x1f/0x30
[16833.924655]  </TASK>

Reported-by: Yanjun Zhang <zhangyanjun@cestc.cn>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Tested-by: Yanjun Zhang <zhangyanjun@cestc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 42c0598..49c9e7b 100644 (file)
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -1620,22 +1620,7 @@ static int nvme_tcp_alloc_queue(struct nvme_ctrl *nctrl, int qid)
        if (ret)
                goto err_init_connect;
 
-       queue->rd_enabled = true;
        set_bit(NVME_TCP_Q_ALLOCATED, &queue->flags);
-       nvme_tcp_init_recv_ctx(queue);
-
-       write_lock_bh(&queue->sock->sk->sk_callback_lock);
-       queue->sock->sk->sk_user_data = queue;
-       queue->state_change = queue->sock->sk->sk_state_change;
-       queue->data_ready = queue->sock->sk->sk_data_ready;
-       queue->write_space = queue->sock->sk->sk_write_space;
-       queue->sock->sk->sk_data_ready = nvme_tcp_data_ready;
-       queue->sock->sk->sk_state_change = nvme_tcp_state_change;
-       queue->sock->sk->sk_write_space = nvme_tcp_write_space;
-#ifdef CONFIG_NET_RX_BUSY_POLL
-       queue->sock->sk->sk_ll_usec = 1;
-#endif
-       write_unlock_bh(&queue->sock->sk->sk_callback_lock);
 
        return 0;
 
@@ -1655,7 +1640,7 @@ err_destroy_mutex:
        return ret;
 }
 
-static void nvme_tcp_restore_sock_calls(struct nvme_tcp_queue *queue)
+static void nvme_tcp_restore_sock_ops(struct nvme_tcp_queue *queue)
 {
        struct socket *sock = queue->sock;
 
@@ -1670,7 +1655,7 @@ static void nvme_tcp_restore_sock_calls(struct nvme_tcp_queue *queue)
 static void __nvme_tcp_stop_queue(struct nvme_tcp_queue *queue)
 {
        kernel_sock_shutdown(queue->sock, SHUT_RDWR);
-       nvme_tcp_restore_sock_calls(queue);
+       nvme_tcp_restore_sock_ops(queue);
        cancel_work_sync(&queue->io_work);
 }
 
@@ -1688,21 +1673,42 @@ static void nvme_tcp_stop_queue(struct nvme_ctrl *nctrl, int qid)
        mutex_unlock(&queue->queue_lock);
 }
 
+static void nvme_tcp_setup_sock_ops(struct nvme_tcp_queue *queue)
+{
+       write_lock_bh(&queue->sock->sk->sk_callback_lock);
+       queue->sock->sk->sk_user_data = queue;
+       queue->state_change = queue->sock->sk->sk_state_change;
+       queue->data_ready = queue->sock->sk->sk_data_ready;
+       queue->write_space = queue->sock->sk->sk_write_space;
+       queue->sock->sk->sk_data_ready = nvme_tcp_data_ready;
+       queue->sock->sk->sk_state_change = nvme_tcp_state_change;
+       queue->sock->sk->sk_write_space = nvme_tcp_write_space;
+#ifdef CONFIG_NET_RX_BUSY_POLL
+       queue->sock->sk->sk_ll_usec = 1;
+#endif
+       write_unlock_bh(&queue->sock->sk->sk_callback_lock);
+}
+
 static int nvme_tcp_start_queue(struct nvme_ctrl *nctrl, int idx)
 {
        struct nvme_tcp_ctrl *ctrl = to_tcp_ctrl(nctrl);
+       struct nvme_tcp_queue *queue = &ctrl->queues[idx];
        int ret;
 
+       queue->rd_enabled = true;
+       nvme_tcp_init_recv_ctx(queue);
+       nvme_tcp_setup_sock_ops(queue);
+
        if (idx)
                ret = nvmf_connect_io_queue(nctrl, idx);
        else
                ret = nvmf_connect_admin_queue(nctrl);
 
        if (!ret) {
-               set_bit(NVME_TCP_Q_LIVE, &ctrl->queues[idx].flags);
+               set_bit(NVME_TCP_Q_LIVE, &queue->flags);
        } else {
-               if (test_bit(NVME_TCP_Q_ALLOCATED, &ctrl->queues[idx].flags))
-                       __nvme_tcp_stop_queue(&ctrl->queues[idx]);
+               if (test_bit(NVME_TCP_Q_ALLOCATED, &queue->flags))
+                       __nvme_tcp_stop_queue(queue);
                dev_err(nctrl->device,
                        "failed to connect queue: %d ret=%d\n", idx, ret);
        }