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Subject[PATCH AUTOSEL 5.4 29/50] memstick: rtsx_usb_ms: fix UAF
Date
From: Tong Zhang <ztong0001@gmail.com>

[ Upstream commit 42933c8aa14be1caa9eda41f65cde8a3a95d3e39 ]

This patch fixes the following issues:
1. memstick_free_host() will free the host, so the use of ms_dev(host) after
it will be a problem. To fix this, move memstick_free_host() after when we
are done with ms_dev(host).
2. In rtsx_usb_ms_drv_remove(), pm need to be disabled before we remove
and free host otherwise memstick_check will be called and UAF will
happen.

[ 11.351173] BUG: KASAN: use-after-free in rtsx_usb_ms_drv_remove+0x94/0x140 [rtsx_usb_ms]
[ 11.357077] rtsx_usb_ms_drv_remove+0x94/0x140 [rtsx_usb_ms]
[ 11.357376] platform_remove+0x2a/0x50
[ 11.367531] Freed by task 298:
[ 11.368537] kfree+0xa4/0x2a0
[ 11.368711] device_release+0x51/0xe0
[ 11.368905] kobject_put+0xa2/0x120
[ 11.369090] rtsx_usb_ms_drv_remove+0x8c/0x140 [rtsx_usb_ms]
[ 11.369386] platform_remove+0x2a/0x50

[ 12.038408] BUG: KASAN: use-after-free in __mutex_lock.isra.0+0x3ec/0x7c0
[ 12.045432] mutex_lock+0xc9/0xd0
[ 12.046080] memstick_check+0x6a/0x578 [memstick]
[ 12.046509] process_one_work+0x46d/0x750
[ 12.052107] Freed by task 297:
[ 12.053115] kfree+0xa4/0x2a0
[ 12.053272] device_release+0x51/0xe0
[ 12.053463] kobject_put+0xa2/0x120
[ 12.053647] rtsx_usb_ms_drv_remove+0xc4/0x140 [rtsx_usb_ms]
[ 12.053939] platform_remove+0x2a/0x50

Signed-off-by: Tong Zhang <ztong0001@gmail.com>
Co-developed-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20210511163944.1233295-1-ztong0001@gmail.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/memstick/host/rtsx_usb_ms.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/memstick/host/rtsx_usb_ms.c b/drivers/memstick/host/rtsx_usb_ms.c
index 102dbb8080da..29271ad4728a 100644
--- a/drivers/memstick/host/rtsx_usb_ms.c
+++ b/drivers/memstick/host/rtsx_usb_ms.c
@@ -799,9 +799,9 @@ static int rtsx_usb_ms_drv_probe(struct platform_device *pdev)

return 0;
err_out:
- memstick_free_host(msh);
pm_runtime_disable(ms_dev(host));
pm_runtime_put_noidle(ms_dev(host));
+ memstick_free_host(msh);
return err;
}

@@ -828,9 +828,6 @@ static int rtsx_usb_ms_drv_remove(struct platform_device *pdev)
}
mutex_unlock(&host->host_mutex);

- memstick_remove_host(msh);
- memstick_free_host(msh);
-
/* Balance possible unbalanced usage count
* e.g. unconditional module removal
*/
@@ -838,10 +835,11 @@ static int rtsx_usb_ms_drv_remove(struct platform_device *pdev)
pm_runtime_put(ms_dev(host));

pm_runtime_disable(ms_dev(host));
- platform_set_drvdata(pdev, NULL);
-
+ memstick_remove_host(msh);
dev_dbg(ms_dev(host),
": Realtek USB Memstick controller has been removed\n");
+ memstick_free_host(msh);
+ platform_set_drvdata(pdev, NULL);

return 0;
}
--
2.30.2
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