usbip: vudc synchronize sysfs code paths

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 # 4.9.x # 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/caabcf3fc87bdae970509b5ff32d05bb7ce2fb15.1616807117.git.skhan@linuxfoundation.org
Signed-off-by: Tom Seewald <tseewald@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/usbip/vudc_dev.c b/drivers/usb/usbip/vudc_dev.c
index 7091848df6c8b54579c231181cfb8be32fa30498..d61b22bb1d8bb9f33c2f98052af1c75b40707bc9 100644 (file)
--- 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 51cc5258b63e5eee56098a186c3f28f465220724..0a4482ced945e7afa9ea5d0cb092a8b485c7c2db 100644 (file)
--- 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 @@ unlock_ud:
        spin_unlock_irq(&udc->ud.lock);
 unlock:
        spin_unlock_irqrestore(&udc->lock, flags);
+       mutex_unlock(&udc->ud.sysfs_lock);
 
        return ret;
 }