linux-kernel - [PATCH] memstick: r592: Fix a UAF bug when removing the driver

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Date:   Sat, 16 Oct 2021 11:26:21 +0000
From:   Zheyu Ma <zheyuma97@...il.com>
To:     maximlevitsky@...il.com, oakad@...oo.com, ulf.hansson@...aro.org
Cc:     linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Zheyu Ma <zheyuma97@...il.com>
Subject: [PATCH] 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 <zheyuma97@...il.com>
---
 drivers/memstick/host/r592.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/memstick/host/r592.c b/drivers/memstick/host/r592.c
index e79a0218c492..1d35d147552d 100644
--- a/drivers/memstick/host/r592.c
+++ b/drivers/memstick/host/r592.c
@@ -838,15 +838,15 @@ static void r592_remove(struct pci_dev *pdev)
 	}
 	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
-- 
2.17.6