This is a note to let you know that I've just added the patch titled can: mcba_usb_start(): add missing urb->transfer_dma initialization to the 4.19-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: can-mcba_usb_start-add-missing-urb-transfer_dma-initialization.patch and it can be found in the queue-4.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From fc43fb69a7af92839551f99c1a96a37b77b3ae7a Mon Sep 17 00:00:00 2001 From: Pavel Skripkin <paskripkin@xxxxxxxxx> Date: Sun, 25 Jul 2021 13:36:30 +0300 Subject: can: mcba_usb_start(): add missing urb->transfer_dma initialization From: Pavel Skripkin <paskripkin@xxxxxxxxx> commit fc43fb69a7af92839551f99c1a96a37b77b3ae7a upstream. 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@xxxxxxxxx Cc: linux-stable <stable@xxxxxxxxxxxxxxx> Reported-by: Yasushi SHOJI <yasushi.shoji@xxxxxxxxx> Signed-off-by: Pavel Skripkin <paskripkin@xxxxxxxxx> Tested-by: Yasushi SHOJI <yashi@xxxxxxxxxxxxxxx> [mkl: fixed typos in commit message - thanks Yasushi SHOJI] Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/net/can/usb/mcba_usb.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/net/can/usb/mcba_usb.c +++ b/drivers/net/can/usb/mcba_usb.c @@ -664,6 +664,8 @@ static int mcba_usb_start(struct mcba_pr 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, Patches currently in stable-queue which might be from paskripkin@xxxxxxxxx are queue-4.19/can-usb_8dev-fix-memory-leak.patch queue-4.19/can-ems_usb-fix-memory-leak.patch queue-4.19/can-esd_usb2-fix-memory-leak.patch queue-4.19/can-mcba_usb_start-add-missing-urb-transfer_dma-initialization.patch