can: mcba_usb: fix memory leak in mcba_usb

stable inclusion
from stable-v4.19.196
commit a115198caaab6d663bef75823a3c5f0802306d60
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9R4I3
CVE: CVE-2021-47231

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a115198caaab6d663bef75823a3c5f0802306d60

--------------------------------

commit 91c02557 upstream.

Syzbot reported memory leak in SocketCAN driver for Microchip CAN BUS
Analyzer Tool. The problem was in unfreed usb_coherent.

In mcba_usb_start() 20 coherent buffers are allocated and there is
nothing, that frees them:

1) In callback function the urb is resubmitted and that's all
2) In disconnect function urbs are simply killed, but URB_FREE_BUFFER
   is not set (see mcba_usb_start) and this flag cannot be used with
   coherent buffers.

Fail log:
| [ 1354.053291][ T8413] mcba_usb 1-1:0.0 can0: device disconnected
| [ 1367.059384][ T8420] kmemleak: 20 new suspected memory leaks (see /sys/kernel/debug/kmem)

So, all allocated buffers should be freed with usb_free_coherent()
explicitly

NOTE:
The same pattern for allocating and freeing coherent buffers
is used in drivers/net/can/usb/kvaser_usb/kvaser_usb_core.c

Fixes: 51f3baad ("can: mcba_usb: Add support for Microchip CAN BUS Analyzer")
Link: https://lore.kernel.org/r/20210609215833.30393-1-paskripkin@gmail.com


Cc: linux-stable <stable@vger.kernel.org>
Reported-and-tested-by:  <syzbot+57281c762a3922e14dfe@syzkaller.appspotmail.com>
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>