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 stub-dev.

Reported-and-tested-by: syzbot+a93fba6d384346a761e3@syzkaller.appspotmail.com Cc: stable@vger.kernel.org Signed-off-by: Shuah Khan skhan@linuxfoundation.org --- drivers/usb/usbip/stub_dev.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/usbip/stub_dev.c b/drivers/usb/usbip/stub_dev.c index 8f1de1fbbeed..d8d3892e5a69 100644 --- a/drivers/usb/usbip/stub_dev.c +++ b/drivers/usb/usbip/stub_dev.c @@ -63,6 +63,7 @@ static ssize_t usbip_sockfd_store(struct device *dev, struct device_attribute *a

dev_info(dev, "stub up\n");

+ mutex_lock(&sdev->ud.sysfs_lock); spin_lock_irq(&sdev->ud.lock);

if (sdev->ud.status != SDEV_ST_AVAILABLE) { @@ -87,13 +88,13 @@ static ssize_t usbip_sockfd_store(struct device *dev, struct device_attribute *a tcp_rx = kthread_create(stub_rx_loop, &sdev->ud, "stub_rx"); if (IS_ERR(tcp_rx)) { sockfd_put(socket); - return -EINVAL; + goto unlock_mutex; } tcp_tx = kthread_create(stub_tx_loop, &sdev->ud, "stub_tx"); if (IS_ERR(tcp_tx)) { kthread_stop(tcp_rx); sockfd_put(socket); - return -EINVAL; + goto unlock_mutex; }

/* get task structs now */ @@ -112,6 +113,8 @@ static ssize_t usbip_sockfd_store(struct device *dev, struct device_attribute *a wake_up_process(sdev->ud.tcp_rx); wake_up_process(sdev->ud.tcp_tx);

+ mutex_unlock(&sdev->ud.sysfs_lock); + } else { dev_info(dev, "stub down\n");

@@ -122,6 +125,7 @@ static ssize_t usbip_sockfd_store(struct device *dev, struct device_attribute *a spin_unlock_irq(&sdev->ud.lock);

usbip_event_add(&sdev->ud, SDEV_EVENT_DOWN); + mutex_unlock(&sdev->ud.sysfs_lock); }

return count; @@ -130,6 +134,8 @@ static ssize_t usbip_sockfd_store(struct device *dev, struct device_attribute *a sockfd_put(socket); err: spin_unlock_irq(&sdev->ud.lock); +unlock_mutex: + mutex_unlock(&sdev->ud.sysfs_lock); return -EINVAL; } static DEVICE_ATTR_WO(usbip_sockfd); @@ -270,6 +276,7 @@ static struct stub_device *stub_device_alloc(struct usb_device *udev) sdev->ud.side = USBIP_STUB; sdev->ud.status = SDEV_ST_AVAILABLE; spin_lock_init(&sdev->ud.lock); + mutex_init(&sdev->ud.sysfs_lock); sdev->ud.tcp_socket = NULL; sdev->ud.sockfd = -1;