can: mcba_usb_start(): add missing urb->transfer_dma initialization

stable inclusion
from stable-v4.19.201
commit ab9597bc0fa772d478fb02b10a7b10b2887b3736
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=ab9597bc0fa772d478fb02b10a7b10b2887b3736

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

commit fc43fb69 upstream.

Yasushi reported, that his Microchip CAN Analyzer stopped working
since commit 91c02557 ("can: mcba_usb: fix memory leak in
mcba_usb"). The problem was in missing urb->transfer_dma
initialization.

In my previous patch to this driver I refactored mcba_usb_start() code
to avoid leaking usb coherent buffers. To archive it, I passed local
stack variable to usb_alloc_coherent() and then saved it to private
array to correctly free all coherent buffers on ->close() call. But I
forgot to initialize urb->transfer_dma with variable passed to
usb_alloc_coherent().

All of this was causing device to not work, since dma addr 0 is not
valid and following log can be found on bug report page, which points
exactly to problem described above.

| DMAR: [DMA Write] Request device [00:14.0] PASID ffffffff fault addr 0 [fault reason 05] PTE Write access is not set

Fixes: 91c02557 ("can: mcba_usb: fix memory leak in mcba_usb")
Link: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=990850
Link: https://lore.kernel.org/r/20210725103630.23864-1-paskripkin@gmail.com


Cc: linux-stable <stable@vger.kernel.org>
Reported-by: Yasushi SHOJI <yasushi.shoji@gmail.com>
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Tested-by: Yasushi SHOJI <yashi@spacecubics.com>
[mkl: fixed typos in commit message - thanks Yasushi SHOJI]
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>