queue-4.4/usb-fix-slab-out-of-bounds-write-in-usb_get_bos_descriptor.patch

   1 From a03ff54460817c76105f81f3aa8ef655759ccc9a Mon Sep 17 00:00:00 2001
   2 From: Alan Stern <stern@rowland.harvard.edu>
   3 Date: Mon, 13 May 2019 13:14:29 -0400
   4 Subject: USB: Fix slab-out-of-bounds write in usb_get_bos_descriptor
   5
   6 From: Alan Stern <stern@rowland.harvard.edu>
   7
   8 commit a03ff54460817c76105f81f3aa8ef655759ccc9a upstream.
   9
  10 The syzkaller USB fuzzer found a slab-out-of-bounds write bug in the
  11 USB core, caused by a failure to check the actual size of a BOS
  12 descriptor.  This patch adds a check to make sure the descriptor is at
  13 least as large as it is supposed to be, so that the code doesn't
  14 inadvertently access memory beyond the end of the allocated region
  15 when assigning to dev->bos->desc->bNumDeviceCaps later on.
  16
  17 Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
  18 Reported-and-tested-by: syzbot+71f1e64501a309fcc012@syzkaller.appspotmail.com
  19 CC: <stable@vger.kernel.org>
  20 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  21
  22 ---
  23  drivers/usb/core/config.c |    4 ++--
  24  1 file changed, 2 insertions(+), 2 deletions(-)
  25
  26 --- a/drivers/usb/core/config.c
  27 +++ b/drivers/usb/core/config.c
  28 @@ -902,8 +902,8 @@ int usb_get_bos_descriptor(struct usb_de
  29
  30         /* Get BOS descriptor */
  31         ret = usb_get_descriptor(dev, USB_DT_BOS, 0, bos, USB_DT_BOS_SIZE);
  32 -       if (ret < USB_DT_BOS_SIZE) {
  33 -               dev_err(ddev, "unable to get BOS descriptor\n");
  34 +       if (ret < USB_DT_BOS_SIZE || bos->bLength < USB_DT_BOS_SIZE) {
  35 +               dev_err(ddev, "unable to get BOS descriptor or descriptor too short\n");
  36                 if (ret >= 0)
  37                         ret = -ENOMSG;
  38                 kfree(bos);