patch "USB: fix error handling in usb_driver_claim_interface()" added to usb-linus

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    USB: fix error handling in usb_driver_claim_interface()

to my usb git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


>From bd729f9d67aa9a303d8925bb8c4f06af25f407d1 Mon Sep 17 00:00:00 2001
From: Alan Stern <stern@rowland.harvard.edu>
Date: Mon, 10 Sep 2018 13:59:59 -0400
Subject: USB: fix error handling in usb_driver_claim_interface()

The syzbot fuzzing project found a use-after-free bug in the USB
core.  The bug was caused by usbfs not unbinding from an interface
when the USB device file was closed, which led another process to
attempt the unbind later on, after the private data structure had been
deallocated.

The reason usbfs did not unbind the interface at the appropriate time
was because it thought the interface had never been claimed in the
first place.  This was caused by the fact that
usb_driver_claim_interface() does not clean up properly when
device_bind_driver() returns an error.  Although the error code gets
passed back to the caller, the iface->dev.driver pointer remains set
and iface->condition remains equal to USB_INTERFACE_BOUND.

This patch adds proper error handling to usb_driver_claim_interface().

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: syzbot+f84aa7209ccec829536f@syzkaller.appspotmail.com
CC: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/core/driver.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index 7652dcb57998..a1f225f077cd 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -550,6 +550,21 @@ int usb_driver_claim_interface(struct usb_driver *driver,
 	if (device_is_registered(dev))
 		retval = device_bind_driver(dev);
 
+	if (retval) {
+		dev->driver = NULL;
+		usb_set_intfdata(iface, NULL);
+		iface->needs_remote_wakeup = 0;
+		iface->condition = USB_INTERFACE_UNBOUND;
+
+		/*
+		 * Unbound interfaces are always runtime-PM-disabled
+		 * and runtime-PM-suspended
+		 */
+		if (driver->supports_autosuspend)
+			pm_runtime_disable(dev);
+		pm_runtime_set_suspended(dev);
+	}
+
 	return retval;
 }
 EXPORT_SYMBOL_GPL(usb_driver_claim_interface);
-- 
2.19.0