From: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx> commit 4e9c93af7279b059faf5bb1897ee90512b258a12 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. This problem is common to all drivers while it can be reproduced easily in vhci_hcd. Add a sysfs_lock to usbip_device struct to protect the paths. Use this in vhci_hcd to protect sysfs paths. For a complete fix, usip_host and usip-vudc drivers and the event handler will have to use this lock to protect the paths. These changes will be done in subsequent patches. Cc: stable@xxxxxxxxxxxxxxx Reported-and-tested-by: syzbot+a93fba6d384346a761e3@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/b6568f7beae702bbc236a545d3c020106ca75eac.1616807117.git.skhan@xxxxxxxxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/usb/usbip/usbip_common.h | 3 +++ drivers/usb/usbip/vhci_hcd.c | 1 + drivers/usb/usbip/vhci_sysfs.c | 30 +++++++++++++++++++++++++----- 3 files changed, 29 insertions(+), 5 deletions(-) --- a/drivers/usb/usbip/usbip_common.h +++ b/drivers/usb/usbip/usbip_common.h @@ -277,6 +277,9 @@ struct usbip_device { /* lock for status */ spinlock_t lock; + /* mutex for synchronizing sysfs store paths */ + struct mutex sysfs_lock; + int sockfd; struct socket *tcp_socket; --- a/drivers/usb/usbip/vhci_hcd.c +++ b/drivers/usb/usbip/vhci_hcd.c @@ -1115,6 +1115,7 @@ static void vhci_device_init(struct vhci vdev->ud.side = USBIP_VHCI; vdev->ud.status = VDEV_ST_NULL; spin_lock_init(&vdev->ud.lock); + mutex_init(&vdev->ud.sysfs_lock); INIT_LIST_HEAD(&vdev->priv_rx); INIT_LIST_HEAD(&vdev->priv_tx); --- a/drivers/usb/usbip/vhci_sysfs.c +++ b/drivers/usb/usbip/vhci_sysfs.c @@ -199,6 +199,8 @@ static int vhci_port_disconnect(struct v usbip_dbg_vhci_sysfs("enter\n"); + mutex_lock(&vdev->ud.sysfs_lock); + /* lock */ spin_lock_irqsave(&vhci->lock, flags); spin_lock(&vdev->ud.lock); @@ -209,6 +211,7 @@ static int vhci_port_disconnect(struct v /* unlock */ spin_unlock(&vdev->ud.lock); spin_unlock_irqrestore(&vhci->lock, flags); + mutex_unlock(&vdev->ud.sysfs_lock); return -EINVAL; } @@ -219,6 +222,8 @@ static int vhci_port_disconnect(struct v usbip_event_add(&vdev->ud, VDEV_EVENT_DOWN); + mutex_unlock(&vdev->ud.sysfs_lock); + return 0; } @@ -363,30 +368,36 @@ static ssize_t store_attach(struct devic else vdev = &vhci->vhci_hcd_hs->vdev[rhport]; + mutex_lock(&vdev->ud.sysfs_lock); + /* Extract socket from fd. */ socket = sockfd_lookup(sockfd, &err); if (!socket) { dev_err(dev, "failed to lookup sock"); - return -EINVAL; + err = -EINVAL; + goto unlock_mutex; } if (socket->type != SOCK_STREAM) { dev_err(dev, "Expecting SOCK_STREAM - found %d", socket->type); sockfd_put(socket); - return -EINVAL; + err = -EINVAL; + goto unlock_mutex; } /* create threads before locking */ tcp_rx = kthread_create(vhci_rx_loop, &vdev->ud, "vhci_rx"); if (IS_ERR(tcp_rx)) { sockfd_put(socket); - return -EINVAL; + err = -EINVAL; + goto unlock_mutex; } tcp_tx = kthread_create(vhci_tx_loop, &vdev->ud, "vhci_tx"); if (IS_ERR(tcp_tx)) { kthread_stop(tcp_rx); sockfd_put(socket); - return -EINVAL; + err = -EINVAL; + goto unlock_mutex; } /* get task structs now */ @@ -411,7 +422,8 @@ static ssize_t store_attach(struct devic * Will be retried from userspace * if there's another free port. */ - return -EBUSY; + err = -EBUSY; + goto unlock_mutex; } dev_info(dev, "pdev(%u) rhport(%u) sockfd(%d)\n", @@ -436,7 +448,15 @@ static ssize_t store_attach(struct devic rh_port_connect(vdev, speed); + dev_info(dev, "Device attached\n"); + + mutex_unlock(&vdev->ud.sysfs_lock); + return count; + +unlock_mutex: + mutex_unlock(&vdev->ud.sysfs_lock); + return err; } static DEVICE_ATTR(attach, S_IWUSR, NULL, store_attach);
