memstick: r592: Fix a UAF bug when removing the driver

In r592_remove(), the driver will free dma after freeing the host, which
may cause a UAF bug.

The following log reveals it:

[ 45.361796 ] BUG: KASAN: use-after-free in r592_remove+0x269/0x350 [r592]
[ 45.364286 ] Call Trace:
[ 45.364472 ] dump_stack_lvl+0xa8/0xd1
[ 45.364751 ] print_address_description+0x87/0x3b0
[ 45.365137 ] kasan_report+0x172/0x1c0
[ 45.365415 ] ? r592_remove+0x269/0x350 [r592]
[ 45.365834 ] ? r592_remove+0x269/0x350 [r592]
[ 45.366168 ] __asan_report_load8_noabort+0x14/0x20
[ 45.366531 ] r592_remove+0x269/0x350 [r592]
[ 45.378785 ]
[ 45.378903 ] Allocated by task 4674:
[ 45.379162 ] ____kasan_kmalloc+0xb5/0xe0
[ 45.379455 ] __kasan_kmalloc+0x9/0x10
[ 45.379730 ] __kmalloc+0x150/0x280
[ 45.379984 ] memstick_alloc_host+0x2a/0x190
[ 45.380664 ]
[ 45.380781 ] Freed by task 5509:
[ 45.381014 ] kasan_set_track+0x3d/0x70
[ 45.381293 ] kasan_set_free_info+0x23/0x40
[ 45.381635 ] ____kasan_slab_free+0x10b/0x140
[ 45.381950 ] __kasan_slab_free+0x11/0x20
[ 45.382241 ] slab_free_freelist_hook+0x81/0x150
[ 45.382575 ] kfree+0x13e/0x290
[ 45.382805 ] memstick_free+0x1c/0x20
[ 45.383070 ] device_release+0x9c/0x1d0
[ 45.383349 ] kobject_put+0x2ef/0x4c0
[ 45.383616 ] put_device+0x1f/0x30
[ 45.383865 ] memstick_free_host+0x24/0x30
[ 45.384162 ] r592_remove+0x242/0x350 [r592]
[ 45.384473 ] pci_device_remove+0xa9/0x250

Signed-off-by: Zheyu Ma <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Ulf Hansson <[e-mail]>

drivers/memstick/host/r592.c

···
 	}
 	memstick_remove_host(dev->host);
 
+	if (dev->dummy_dma_page)
+		dma_free_coherent(&pdev->dev, PAGE_SIZE, dev->dummy_dma_page,
+			dev->dummy_dma_page_physical_address);
+
 	free_irq(dev->irq, dev);
 	iounmap(dev->mmio);
 	pci_release_regions(pdev);
 	pci_disable_device(pdev);
 	memstick_free_host(dev->host);
-
-	if (dev->dummy_dma_page)
-		dma_free_coherent(&pdev->dev, PAGE_SIZE, dev->dummy_dma_page,
-			dev->dummy_dma_page_physical_address);
 }
 
 #ifdef CONFIG_PM_SLEEP