vhci_shutdown_connection() references connection state (tcp_socket, tcp_rx, tcp_tx, sockfd) saved in usbpip_device without holding the lock.
Current connection tear down sequence: Step 1: shutdown the socket Step 2: stop rx thread and reset tcp_rx pointer Step 3: stop tx thread and reset tcp_tx pointer Step 4: Reset tcp_socket and sockfd There are several race windows between these steps. In addition, device reset routine (vhci_device_reset) resets tcp_socket and sockfd holding the lock. Fix these races: - Introduce in_disconnect flag to ensure vhci_shutdown_connection() runs only once. - Change attach_store() to initialize in_disconnect to false while initializing connection status (tcp_socket, tcp_rx, tcp_tx, sockfd) - Change vhci_shutdown_connection() to check in_disconnect and bail out if disconnect is in progress. - Change vhci_shutdown_connection() to -- hold lock to save connection state pointers and unlock. -- Shutdown the socket and stop threads. -- Hold lock to clear connection status and in_disconnect flag. - Change vhci_device_reset() to reset tcp_socket and sockfd. if !in_disconnect Tested syzbot and the reproducer did not trigger any issue. Reported-and-tested-by: [email protected] Signed-off-by: Shuah Khan <[email protected]> --- drivers/usb/usbip/usbip_common.h | 1 + drivers/usb/usbip/vhci_hcd.c | 55 +++++++++++++++++++++++--------- drivers/usb/usbip/vhci_sysfs.c | 4 +++ 3 files changed, 45 insertions(+), 15 deletions(-) diff --git a/drivers/usb/usbip/usbip_common.h b/drivers/usb/usbip/usbip_common.h index d60ce17d3dd2..f6261c5a8c91 100644 --- a/drivers/usb/usbip/usbip_common.h +++ b/drivers/usb/usbip/usbip_common.h @@ -268,6 +268,7 @@ struct usbip_device { struct task_struct *tcp_rx; struct task_struct *tcp_tx; + bool in_disconnect; /* run device disconnect just once */ unsigned long event; wait_queue_head_t eh_waitq; diff --git a/drivers/usb/usbip/vhci_hcd.c b/drivers/usb/usbip/vhci_hcd.c index 3209b5ddd30c..c1917efe5737 100644 --- a/drivers/usb/usbip/vhci_hcd.c +++ b/drivers/usb/usbip/vhci_hcd.c @@ -1007,31 +1007,54 @@ static void vhci_device_unlink_cleanup(struct vhci_device *vdev) static void vhci_shutdown_connection(struct usbip_device *ud) { struct vhci_device *vdev = container_of(ud, struct vhci_device, ud); + unsigned long flags; + struct socket *socket; + struct task_struct *tcp_rx = NULL; + struct task_struct *tcp_tx = NULL; + int sockfd = 0; + + spin_lock_irqsave(&ud->lock, flags); + if (vdev->ud.in_disconnect) { + pr_info("%s: Disconnect in progress for sockfd %d\n", + __func__, ud->sockfd); + spin_unlock_irqrestore(&ud->lock, flags); + return; + } + vdev->ud.in_disconnect = true; + socket = ud->tcp_socket; + tcp_rx = vdev->ud.tcp_rx; + tcp_tx = vdev->ud.tcp_tx; + sockfd = ud->sockfd; + spin_unlock_irqrestore(&ud->lock, flags); /* need this? see stub_dev.c */ - if (ud->tcp_socket) { - pr_debug("shutdown tcp_socket %d\n", ud->sockfd); - kernel_sock_shutdown(ud->tcp_socket, SHUT_RDWR); + if (socket) { + pr_info("%s: shutdown tcp_socket %d\n", __func__, sockfd); + kernel_sock_shutdown(socket, SHUT_RDWR); } - /* kill threads related to this sdev */ - if (vdev->ud.tcp_rx) { - kthread_stop_put(vdev->ud.tcp_rx); - vdev->ud.tcp_rx = NULL; + /* kill threads related to this vdev */ + if (tcp_rx) { + pr_info("%s: stop rx thread\n", __func__); + kthread_stop_put(tcp_rx); } - if (vdev->ud.tcp_tx) { - kthread_stop_put(vdev->ud.tcp_tx); - vdev->ud.tcp_tx = NULL; + if (tcp_tx) { + pr_info("%s: stop tx thread\n", __func__); + kthread_stop_put(tcp_tx); } - pr_info("stop threads\n"); + spin_lock_irqsave(&ud->lock, flags); /* active connection is closed */ - if (vdev->ud.tcp_socket) { + if (ud->tcp_socket) { + vdev->ud.tcp_rx = NULL; + vdev->ud.tcp_tx = NULL; sockfd_put(vdev->ud.tcp_socket); vdev->ud.tcp_socket = NULL; vdev->ud.sockfd = -1; } - pr_info("release socket\n"); + vdev->ud.in_disconnect = false; + spin_unlock_irqrestore(&ud->lock, flags); + pr_info("%s: release socket\n", __func__); vhci_device_unlink_cleanup(vdev); @@ -1057,7 +1080,7 @@ static void vhci_shutdown_connection(struct usbip_device *ud) */ rh_port_disconnect(vdev); - pr_info("disconnect device\n"); + pr_info("%s: disconnect device\n", __func__); } static void vhci_device_reset(struct usbip_device *ud) @@ -1073,7 +1096,9 @@ static void vhci_device_reset(struct usbip_device *ud) usb_put_dev(vdev->udev); vdev->udev = NULL; - if (ud->tcp_socket) { + if (!vdev->ud.in_disconnect && ud->tcp_socket) { + pr_info("%s: release tcp_socket %d\n", + __func__, ud->sockfd); sockfd_put(ud->tcp_socket); ud->tcp_socket = NULL; ud->sockfd = -1; diff --git a/drivers/usb/usbip/vhci_sysfs.c b/drivers/usb/usbip/vhci_sysfs.c index c4b4256e5dad..c4457026d5ad 100644 --- a/drivers/usb/usbip/vhci_sysfs.c +++ b/drivers/usb/usbip/vhci_sysfs.c @@ -412,6 +412,10 @@ static ssize_t attach_store(struct device *dev, struct device_attribute *attr, vdev->ud.tcp_rx = tcp_rx; vdev->ud.tcp_tx = tcp_tx; vdev->ud.status = VDEV_ST_NOTASSIGNED; + + /* used to run socket shutdown just once */ + vdev->ud.in_disconnect = false; + usbip_kcov_handle_init(&vdev->ud); spin_unlock(&vdev->ud.lock); -- 2.27.0
