The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From bd8b82042269a95db48074b8bb400678dbac1815 Mon Sep 17 00:00:00 2001
From: Shuah Khan skhan@linuxfoundation.org Date: Mon, 29 Mar 2021 19:36:50 -0600 Subject: [PATCH] usbip: vudc synchronize sysfs code paths
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 Reported-and-tested-by: syzbot+a93fba6d384346a761e3@syzkaller.appspotmail.com Signed-off-by: Shuah Khan skhan@linuxfoundation.org Link: https://lore.kernel.org/r/caabcf3fc87bdae970509b5ff32d05bb7ce2fb15.161680711... 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 c8eeabdd9b56..2bc428f2e261 100644 --- a/drivers/usb/usbip/vudc_dev.c +++ b/drivers/usb/usbip/vudc_dev.c @@ -572,6 +572,7 @@ 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 7383a543c6d1..f7633ee655a1 100644 --- a/drivers/usb/usbip/vudc_sysfs.c +++ b/drivers/usb/usbip/vudc_sysfs.c @@ -112,6 +112,7 @@ static ssize_t usbip_sockfd_store(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) { @@ -187,6 +188,8 @@ static ssize_t usbip_sockfd_store(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 { @@ -207,6 +210,7 @@ static ssize_t usbip_sockfd_store(struct device *dev, }
spin_unlock_irqrestore(&udc->lock, flags); + mutex_unlock(&udc->ud.sysfs_lock);
return count;
@@ -216,6 +220,7 @@ static ssize_t usbip_sockfd_store(struct device *dev, spin_unlock_irq(&udc->ud.lock); unlock: spin_unlock_irqrestore(&udc->lock, flags); + mutex_unlock(&udc->ud.sysfs_lock);
return ret; }