From: Shuah Khan skhan@linuxfoundation.org

commit bd8b82042269a95db48074b8bb400678dbac1815 upstream.

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 # 4.14.x Reported-and-tested-by: syzbot+a93fba6d384346a761e3@syzkaller.appspotmail.com Signed-off-by: Shuah Khan skhan@linuxfoundation.org Link: https://lore.kernel.org/r/caabcf3fc87bdae970509b5ff32d05bb7ce2fb15.161680711... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Tom Seewald tseewald@gmail.com --- drivers/usb/usbip/vudc_dev.c | 1 + drivers/usb/usbip/vudc_sysfs.c | 5 +++++ 2 files changed, 6 insertions(+)

diff --git a/drivers/usb/usbip/vudc_dev.c b/drivers/usb/usbip/vudc_dev.c index 7091848df6c8..d61b22bb1d8b 100644 --- a/drivers/usb/usbip/vudc_dev.c +++ b/drivers/usb/usbip/vudc_dev.c @@ -582,6 +582,7 @@ 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;

diff --git a/drivers/usb/usbip/vudc_sysfs.c b/drivers/usb/usbip/vudc_sysfs.c index f44d98eeb36a..e9d8dbd4e5a4 100644 --- a/drivers/usb/usbip/vudc_sysfs.c +++ b/drivers/usb/usbip/vudc_sysfs.c @@ -125,6 +125,7 @@ static ssize_t store_sockfd(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) { @@ -200,6 +201,8 @@ static ssize_t store_sockfd(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 { @@ -220,6 +223,7 @@ static ssize_t store_sockfd(struct device *dev, }

spin_unlock_irqrestore(&udc->lock, flags); + mutex_unlock(&udc->ud.sysfs_lock);

return count;

@@ -229,6 +233,7 @@ static ssize_t store_sockfd(struct device *dev, spin_unlock_irq(&udc->ud.lock); unlock: spin_unlock_irqrestore(&udc->lock, flags); + mutex_unlock(&udc->ud.sysfs_lock);

return ret; }