[PATCH v3] usbdevfs: Fix broken scatter-gather transfer

[PATCH v3] usbdevfs: Fix broken scatter-gather transfer

[Henrik Rydberg]

The handling of large output bulk transfers is broken; the same user
page is read over and over again. Fixed with this patch.

Cc: stable@kernel.org
Acked-by: Peter Stuge <peter@stuge.se>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
---
Hi Greg,

Here is the formal and third version of the patch. Version two still
made me nervous, so I moved the increment to where it is clear that
the buffer pointer is never referenced again later in the function. I
still kept the ACKS, hope that is alright with everyone.

Thanks,
Henrik

 drivers/usb/core/devio.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index ebb8a9d..7f75343 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -1348,6 +1348,7 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb,
 					ret = -EFAULT;
 					goto error;
 				}
+				uurb->buffer += u;
 			}
 			totlen -= u;
 		}
-- 
1.7.12.2

Re: [PATCH v3] usbdevfs: Fix broken scatter-gather transfer

[Hans de Goede]

Hi,

On 10/13/2012 12:20 PM, Henrik Rydberg wrote:
> The handling of large output bulk transfers is broken; the same user
> page is read over and over again. Fixed with this patch.
>
> Cc: stable@kernel.org
> Acked-by: Peter Stuge <peter@stuge.se>
> Acked-by: Hans de Goede <hdegoede@redhat.com>
> Acked-by: Alan Stern <stern@rowland.harvard.edu>
> Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
> ---
> Hi Greg,
>
> Here is the formal and third version of the patch. Version two still
> made me nervous,

And it should, as as said before I believe it would have broken large
input transfers ...

  so I moved the increment to where it is clear that
> the buffer pointer is never referenced again later in the function. I
> still kept the ACKS, hope that is alright with everyone.

Unlike the previous one, this version should work, so yes it may keep
my ACK :)

Regards,

Hans

>
> Thanks,
> Henrik
>
>   drivers/usb/core/devio.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
> index ebb8a9d..7f75343 100644
> --- a/drivers/usb/core/devio.c
> +++ b/drivers/usb/core/devio.c
> @@ -1348,6 +1348,7 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb,
>   					ret = -EFAULT;
>   					goto error;
>   				}
> +				uurb->buffer += u;
>   			}
>   			totlen -= u;
>   		}
>