tree 7bc6b78af6fa9c2d12dce25f72a96712442bf09c
parent cdddc62b2f0f64f8c60a9bbb673452cd3bd4e62e
author Mathias Nyman <mathias.nyman@linux.intel.com> 1535978656 +0300
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1537943796 +0200

usb: Avoid use-after-free by flushing endpoints early in usb_set_interface()

commit f9a5b4f58b280c1d26255376713c132f93837621 upstream.

The steps taken by usb core to set a new interface is very different from
what is done on the xHC host side.

xHC hardware will do everything in one go. One command is used to set up
new endpoints, free old endpoints, check bandwidth, and run the new
endpoints.

All this is done by xHC when usb core asks the hcd to check for
available bandwidth. At this point usb core has not yet flushed the old
endpoints, which will cause use-after-free issues in xhci driver as
queued URBs are cancelled on a re-allocated endpoint.

To resolve this add a call to usb_disable_interface() which will flush
the endpoints before calling usb_hcd_alloc_bandwidth()

Additional checks in xhci driver will also be implemented to gracefully
handle stale URB cancel on freed and re-allocated endpoints

Cc: <stable@vger.kernel.org>
Reported-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>