linux-kernel - [PATCH] misc: hisi_hikey_usb: Fix use after free bug in hisi_hikey_usb

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Message-Id: <20230312145305.1908607-1-zyytlz.wz@163.com>
Date:   Sun, 12 Mar 2023 22:53:05 +0800
From:   Zheng Wang <zyytlz.wz@....com>
To:     jstultz@...gle.com
Cc:     arnd@...db.de, gregkh@...uxfoundation.org,
        linux-kernel@...r.kernel.org, hackerzheng666@...il.com,
        1395428693sheep@...il.com, alex000young@...il.com,
        Zheng Wang <zyytlz.wz@....com>
Subject: [PATCH] misc: hisi_hikey_usb: Fix use after free bug in hisi_hikey_usb_remove due to race condition

In hisi_hikey_usb_probe, it called hisi_hikey_usb_of_role_switch
and bound &hisi_hikey_usb->work with relay_set_role_switch.
When it calls hub_usb_role_switch_set, it will finally call
schedule_work to start the work.

When we call hisi_hikey_usb_remove to remove the driver, there
may be a sequence as follows:

Fix it by finishing the work before cleanup in hisi_hikey_usb_remove.

CPU0                  CPU1

                    |relay_set_role_switch
hisi_hikey_usb_remove|
  usb_role_switch_put|
    usb_role_switch_release  |
     kfree(sw)     |
                    | usb_role_switch_set_role
                    |   //use

Fixes: 7a6ff4c4cbc3 ("misc: hisi_hikey_usb: Driver to support onboard USB gpio hub on Hikey960")
Signed-off-by: Zheng Wang <zyytlz.wz@....com>
---
 drivers/misc/hisi_hikey_usb.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/misc/hisi_hikey_usb.c b/drivers/misc/hisi_hikey_usb.c
index 2165ec35a343..26fc895c4418 100644
--- a/drivers/misc/hisi_hikey_usb.c
+++ b/drivers/misc/hisi_hikey_usb.c
@@ -242,6 +242,7 @@ static int hisi_hikey_usb_probe(struct platform_device *pdev)
 static int  hisi_hikey_usb_remove(struct platform_device *pdev)
 {
 	struct hisi_hikey_usb *hisi_hikey_usb = platform_get_drvdata(pdev);
+	cancel_work_sync(&hisi_hikey_usb->work);
 
 	if (hisi_hikey_usb->hub_role_sw) {
 		usb_role_switch_unregister(hisi_hikey_usb->hub_role_sw);
-- 
2.25.1