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@xxxxxxxxxxxxxxxxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
---
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;
--
2.27.0
