From: Pavel Skripkin paskripkin@gmail.com

Yasushi reported, that his Microchip CAN Analyzer stopped working since commit 91c02557174b ("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: 91c02557174b ("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 --- drivers/net/can/usb/mcba_usb.c | 2 ++ 1 file changed, 2 insertions(+)

diff --git a/drivers/net/can/usb/mcba_usb.c b/drivers/net/can/usb/mcba_usb.c index a45865bd7254..a1a154c08b7f 100644 --- a/drivers/net/can/usb/mcba_usb.c +++ b/drivers/net/can/usb/mcba_usb.c @@ -653,6 +653,8 @@ static int mcba_usb_start(struct mcba_priv *priv) break; }

+ urb->transfer_dma = buf_dma; + usb_fill_bulk_urb(urb, priv->udev, usb_rcvbulkpipe(priv->udev, MCBA_USB_EP_IN), buf, MCBA_USB_RX_BUFF_SIZE,