usb: atm: ueagle-atm: reject descriptors that confuse probe and disconnect

usb: atm: ueagle-atm: reject descriptors that confuse probe and disconnect

uea_probe() distinguishes a pre-firmware device from a post-firmware one
using the USB id (UEA_IS_PREFIRM()), and stores a different object as the
interface data in each case: a 'struct completion' for a pre-firmware
device (to be waited on in .disconnect()), or a 'struct usbatm_data' for a
post-firmware one.

uea_disconnect() instead tells the two apart by the number of interfaces
of the active configuration (a pre-firmware device exposes a single
interface, ADI930 has 2 and eagle has 3), and casts the interface data
accordingly.

Because the two handlers use different criteria, a crafted device that
advertises a pre-firmware id together with a multi-interface descriptor
(or a post-firmware id with a single interface) makes them disagree: the
small 'struct completion' stored by uea_probe() is then passed to
usbatm_usb_disconnect(), which casts it to 'struct usbatm_data' and takes
instance->serialize, reading past the end of the allocation:

  BUG: KASAN: slab-out-of-bounds in __mutex_lock+0x152a/0x1b80
  Read of size 8 at addr ffff8880470e2c60 by task kworker/1:2/982
  ...
   __mutex_lock+0x152a/0x1b80
   usbatm_usb_disconnect+0x70/0x820
   uea_disconnect+0x133/0x2c0
   usb_unbind_interface+0x1dd/0x9e0
  ...
  which belongs to the cache kmalloc-96 of size 96
  The buggy address is located 0 bytes to the right of
   allocated 96-byte region [ffff8880470e2c00, ffff8880470e2c60)

Reject such inconsistent descriptors in uea_probe() so that both handlers
always make the same pre/post-firmware decision.

Reported-by: syzbot+e62a973f8322b3bbe3ac@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=e62a973f8322b3bbe3ac
Fixes: e2674dfbed8a ("usb: atm: ueagle-atm: wait for pre-firmware load in .disconnect()")
Signed-off-by: Diego Fernando Mancera Gomez <diegomancera.dev@gmail.com>
Acked-by: Stanislaw Gruszka <stf_xl@wp.pl>
Link: https://patch.msgid.link/20260717080704.1264-1-diegomancera.dev@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>