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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Shuah Khan <shuahkh@osg.samsung.com>
Subject: [PATCH 4.4 05/44] usbip: usbip_host: fix to hold parent lock for device_attach() calls
Date:   Mon, 30 Apr 2018 12:24:16 -0700
Message-Id: <20180430190946.548163410@linuxfoundation.org>
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4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Shuah Khan <shuahkh@osg.samsung.com>

commit 4bfb141bc01312a817d36627cc47c93f801c216d upstream.

usbip_host calls device_attach() without holding dev->parent lock.
Fix it.

Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/usb/usbip/stub_main.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/usb/usbip/stub_main.c
+++ b/drivers/usb/usbip/stub_main.c
@@ -201,7 +201,12 @@ static ssize_t rebind_store(struct devic
 	if (!bid)
 		return -ENODEV;
 
+	/* device_attach() callers should hold parent lock for USB */
+	if (bid->udev->dev.parent)
+		device_lock(bid->udev->dev.parent);
 	ret = device_attach(&bid->udev->dev);
+	if (bid->udev->dev.parent)
+		device_unlock(bid->udev->dev.parent);
 	if (ret < 0) {
 		dev_err(&bid->udev->dev, "rebind failed\n");
 		return ret;