nvme: fix admin request_queue lifetime

The namespaces can access the controller's admin request_queue, and
stale references on the namespaces may exist after tearing down the
controller. Ensure the admin request_queue is active by moving the
controller's 'put' to after all controller references have been released
to ensure no one is can access the request_queue. This fixes a reported
use-after-free bug:

  BUG: KASAN: slab-use-after-free in blk_queue_enter+0x41c/0x4a0
  Read of size 8 at addr ffff88c0a53819f8 by task nvme/3287
  CPU: 67 UID: 0 PID: 3287 Comm: nvme Tainted: G            E       6.13.2-ga1582f1a031e #15
  Tainted: [E]=UNSIGNED_MODULE
  Hardware name: Jabil /EGS 2S MB1, BIOS 1.00 06/18/2025
  Call Trace:
   <TASK>
   dump_stack_lvl+0x4f/0x60
   print_report+0xc4/0x620
   ? _raw_spin_lock_irqsave+0x70/0xb0
   ? _raw_read_unlock_irqrestore+0x30/0x30
   ? blk_queue_enter+0x41c/0x4a0
   kasan_report+0xab/0xe0
   ? blk_queue_enter+0x41c/0x4a0
   blk_queue_enter+0x41c/0x4a0
   ? __irq_work_queue_local+0x75/0x1d0
   ? blk_queue_start_drain+0x70/0x70
   ? irq_work_queue+0x18/0x20
   ? vprintk_emit.part.0+0x1cc/0x350
   ? wake_up_klogd_work_func+0x60/0x60
   blk_mq_alloc_request+0x2b7/0x6b0
   ? __blk_mq_alloc_requests+0x1060/0x1060
   ? __switch_to+0x5b7/0x1060
   nvme_submit_user_cmd+0xa9/0x330
   nvme_user_cmd.isra.0+0x240/0x3f0
   ? force_sigsegv+0xe0/0xe0
   ? nvme_user_cmd64+0x400/0x400
   ? vfs_fileattr_set+0x9b0/0x9b0
   ? cgroup_update_frozen_flag+0x24/0x1c0
   ? cgroup_leave_frozen+0x204/0x330
   ? nvme_ioctl+0x7c/0x2c0
   blkdev_ioctl+0x1a8/0x4d0
   ? blkdev_common_ioctl+0x1930/0x1930
   ? fdget+0x54/0x380
   __x64_sys_ioctl+0x129/0x190
   do_syscall_64+0x5b/0x160
   entry_SYSCALL_64_after_hwframe+0x4b/0x53
  RIP: 0033:0x7f765f703b0b
  Code: ff ff ff 85 c0 79 9b 49 c7 c4 ff ff ff ff 5b 5d 4c 89 e0 41 5c c3 66 0f 1f 84 00 00 00 00 00 f3 0f 1e fa b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d dd 52 0f 00 f7 d8 64 89 01 48
  RSP: 002b:00007ffe2cefe808 EFLAGS: 00000202 ORIG_RAX: 0000000000000010
  RAX: ffffffffffffffda RBX: 00007ffe2cefe860 RCX: 00007f765f703b0b
  RDX: 00007ffe2cefe860 RSI: 00000000c0484e41 RDI: 0000000000000003
  RBP: 0000000000000000 R08: 0000000000000003 R09: 0000000000000000
  R10: 00007f765f611d50 R11: 0000000000000202 R12: 0000000000000003
  R13: 00000000c0484e41 R14: 0000000000000001 R15: 00007ffe2cefea60
   </TASK>

Reported-by: Casey Chen <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Reviewed-by: Hannes Reinecke <[email protected]>
Reviewed-by: Ming Lei <[email protected]>
Reviewed-by: Chaitanya Kulkarni <[email protected]>
Signed-off-by: Keith Busch <[email protected]>

Author: keithbusch

drivers/nvme/host/core.c

@@ -4901,7 +4901,6 @@ void nvme_remove_admin_tag_set(struct nvme_ctrl *ctrl)
 	 */
 	nvme_stop_keep_alive(ctrl);
 	blk_mq_destroy_queue(ctrl->admin_q);
-	blk_put_queue(ctrl->admin_q);
 	if (ctrl->ops->flags & NVME_F_FABRICS) {
 		blk_mq_destroy_queue(ctrl->fabrics_q);
 		blk_put_queue(ctrl->fabrics_q);
@@ -5045,6 +5044,8 @@ static void nvme_free_ctrl(struct device *dev)
 		container_of(dev, struct nvme_ctrl, ctrl_device);
 	struct nvme_subsystem *subsys = ctrl->subsys;
 
+	if (ctrl->admin_q)
+		blk_put_queue(ctrl->admin_q);
 	if (!subsys || ctrl->instance != subsys->instance)
 		ida_free(&nvme_instance_ida, ctrl->instance);
 	nvme_free_cels(ctrl);