--- /dev/null
+From 845d584f41eac3475c21e4a7d5e88d0f6e410cf7 Mon Sep 17 00:00:00 2001
+From: Hans de Goede <hdegoede@redhat.com>
+Date: Mon, 16 Oct 2017 16:21:19 +0200
+Subject: USB: devio: Revert "USB: devio: Don't corrupt user memory"
+
+From: Hans de Goede <hdegoede@redhat.com>
+
+commit 845d584f41eac3475c21e4a7d5e88d0f6e410cf7 upstream.
+
+Taking the uurb->buffer_length userspace passes in as a maximum for the
+actual urbs transfer_buffer_length causes 2 serious issues:
+
+1) It breaks isochronous support for all userspace apps using libusb,
+ as existing libusb versions pass in 0 for uurb->buffer_length,
+ relying on the kernel using the lenghts of the usbdevfs_iso_packet_desc
+ descriptors passed in added together as buffer length.
+
+ This for example causes redirection of USB audio and Webcam's into
+ virtual machines using qemu-kvm to no longer work. This is a userspace
+ ABI break and as such must be reverted.
+
+ Note that the original commit does not protect other users / the
+ kernels memory, it only stops the userspace process making the call
+ from shooting itself in the foot.
+
+2) It may cause the kernel to program host controllers to DMA over random
+ memory. Just as the devio code used to only look at the iso_packet_desc
+ lenghts, the host drivers do the same, relying on the submitter of the
+ urbs to make sure the entire buffer is large enough and not checking
+ transfer_buffer_length.
+
+ But the "USB: devio: Don't corrupt user memory" commit now takes the
+ userspace provided uurb->buffer_length for the buffer-size while copying
+ over the user-provided iso_packet_desc lengths 1:1, allowing the user
+ to specify a small buffer size while programming the host controller to
+ dma a lot more data.
+
+ (Atleast the ohci, uhci, xhci and fhci drivers do not check
+ transfer_buffer_length for isoc transfers.)
+
+This reverts commit fa1ed74eb1c2 ("USB: devio: Don't corrupt user memory")
+fixing both these issues.
+
+Cc: Dan Carpenter <dan.carpenter@oracle.com>
+Signed-off-by: Hans de Goede <hdegoede@redhat.com>
+Acked-by: Alan Stern <stern@rowland.harvard.edu>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ drivers/usb/core/devio.c | 6 +-----
+ 1 file changed, 1 insertion(+), 5 deletions(-)
+
+--- a/drivers/usb/core/devio.c
++++ b/drivers/usb/core/devio.c
+@@ -1413,11 +1413,7 @@ static int proc_do_submiturb(struct usb_
+ totlen += isopkt[u].length;
+ }
+ u *= sizeof(struct usb_iso_packet_descriptor);
+- if (totlen <= uurb->buffer_length)
+- uurb->buffer_length = totlen;
+- else
+- WARN_ONCE(1, "uurb->buffer_length is too short %d vs %d",
+- totlen, uurb->buffer_length);
++ uurb->buffer_length = totlen;
+ break;
+
+ default: