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FAILED: patch "[PATCH] usbip: stub-dev synchronize sysfs code paths" failed to apply to 4.9-stable tree

PATCH [email protected] 1 participant 1 message Apr 11, 2021

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Stable branch USB USB over IP driver
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The patch below does not apply to the 4.9-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 <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 9dbf34a834563dada91366c2ac266f32ff34641a Mon Sep 17 00:00:00 2001
From: Shuah Khan <[email protected]>
Date: Mon, 29 Mar 2021 19:36:49 -0600
Subject: [PATCH] usbip: stub-dev 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 stub-dev.

Cc [email protected]
Reported-and-tested-by [email protected]
Signed-off-by Shuah Khan <[email protected]>
Link https://lore.kernel.org/r/2b182f3561b4a065bf3bf6dce3b0e9944ba17b3f.1616807117.git.skhan@linuxfoundation.org open here
Signed-off-by Greg Kroah-Hartman <[email protected]>
drivers/usb/usbip/stub_dev.c +9 -2
index 8f1de1fbbeed..d8d3892e5a69 100644
@@ -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 @@ sock_err:
 	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;