Commit bd8b8204 authored by Shuah Khan's avatar Shuah Khan Committed by Greg Kroah-Hartman
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usbip: vudc synchronize sysfs code paths 



Fuzzing uncovered race condition between sysfs code paths in usbip
drivers. Device connect/disconnect code paths initiated through
sysfs interface are prone to races if disconnect happens during
connect and vice versa.

Use sysfs_lock to protect sysfs paths in vudc.

Cc: stable@vger.kernel.org
Reported-and-tested-by: default avatar <syzbot+a93fba6d384346a761e3@syzkaller.appspotmail.com>
Signed-off-by: default avatarShuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/caabcf3fc87bdae970509b5ff32d05bb7ce2fb15.1616807117.git.skhan@linuxfoundation.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 9dbf34a8

drivers/usb/usbip/vudc_dev.c

+1 −0
Original line number Diff line number Diff line
@@ -572,6 +572,7 @@ static int init_vudc_hw(struct vudc *udc) 
	init_waitqueue_head(&udc->tx_waitq);



	spin_lock_init(&ud->lock);

	mutex_init(&ud->sysfs_lock);

	ud->status = SDEV_ST_AVAILABLE;

	ud->side = USBIP_VUDC;

drivers/usb/usbip/vudc_sysfs.c

+5 −0
Original line number Diff line number Diff line
@@ -112,6 +112,7 @@ static ssize_t usbip_sockfd_store(struct device *dev, 
		dev_err(dev, "no device");

		return -ENODEV;

	}

	mutex_lock(&udc->ud.sysfs_lock);

	spin_lock_irqsave(&udc->lock, flags);

	/* Don't export what we don't have */

	if (!udc->driver || !udc->pullup) {
@@ -187,6 +188,8 @@ static ssize_t usbip_sockfd_store(struct device *dev, 


		wake_up_process(udc->ud.tcp_rx);

		wake_up_process(udc->ud.tcp_tx);



		mutex_unlock(&udc->ud.sysfs_lock);

		return count;



	} else {
@@ -207,6 +210,7 @@ static ssize_t usbip_sockfd_store(struct device *dev, 
	}



	spin_unlock_irqrestore(&udc->lock, flags);

	mutex_unlock(&udc->ud.sysfs_lock);



	return count;
@@ -216,6 +220,7 @@ static ssize_t usbip_sockfd_store(struct device *dev, 
	spin_unlock_irq(&udc->ud.lock);

unlock:

	spin_unlock_irqrestore(&udc->lock, flags);

	mutex_unlock(&udc->ud.sysfs_lock);



	return ret;

}