USBFS Bugfix

[Stefan Bader]

Chase Douglas wrote:
> On Wed, Mar 24, 2010 at 12:39 PM, Stefan Bader
> <stefan.bader at canonical.com> wrote:
>> Chase Douglas wrote:
>>> Hi Markus,
>>>
>>> On Wed, Mar 24, 2010 at 12:21 PM, Markus Rechberger
>>> <mrechberger at gmail.com> wrote:
>>>> Hi,
>>>>
>>>> on IRC I was recommended to submit this information to the mailinglist
>>>>
>>>> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/544527
>>> The bug itself doesn't list much information. It basically says "usbfs
>>> is broken." We need some proof of what is going wrong, preferably
>>> something that can be tested when a fix is available.
>>>
>>>> Here's a better solution.  In theory we could copy just the individual
>>>> packets from within the transfer buffer, but that would probably take
>>>> longer than simply copying the whole buffer.
>>>>
>>>> (This was a little hasty; I haven't even compile-tested the patch.
>>>> Some small fixes may be needed.)
>>> The general procedure for fixes to reach Ubuntu is to have them sent
>>> upstream and be included in the mainline linux, and then to have the
>>> fix read the -stable tree. We then pull patches from the -stable tree
>>> for inclusion in Ubuntu.
>>>
>>> If you can show that a specific patch has been found to fix an issue
>>> in Ubuntu and it has been accepted upstream by the maintainers of the
>>> kernel subsystem this impacts, we may be able to accept the patch as a
>>> pre-stable fix, in anticipation that it will be accepted into the
>>> -stable tree in the future.
>>>
>>> What is the origin of this patch? Is it from upstream somewhere? A
>>> commit hash from linux-2.6 or some other tree would be very helpful.
>>>
>>>> Alan Stern
>>>>
>>>>
>>>> -----------------------------------------------------------------------
>>>> This patch fixes a bug in the way isochronous input data is returned
>>>> to userspace for usbfs transfers.  The entire buffer must be copied,
>>>> not just the first actual_length bytes, because the individual packets
>>>> will be discontiguous if any of them are short.
>>>>
>>>> Signed-off-by: Alan Stern <stern at rowland.harvard.edu>
>>>> CC: stable <stable at kernel.org>
>>>>
>>>> ---
>>>> Index: usb-2.6/drivers/usb/core/devio.c
>>>> ===================================================================
>>>> --- usb-2.6.orig/drivers/usb/core/devio.c
>>>> +++ usb-2.6/drivers/usb/core/devio.c
>>>> @@ -1176,6 +1176,13 @@ static int proc_do_submiturb(struct dev_
>>>>                        free_async(as);
>>>>                        return -ENOMEM;
>>>>                }
>>>> +               /* Isochronous input data may end up being discontiguous
>>>> +                * if some of the packets are short.  Clear the buffer so
>>>> +                * that the gaps don't leak kernel data to userspace.
>>>> +                */
>>>> +               if (is_in && uurb->type == USBDEVFS_URB_TYPE_ISO)
>>>> +                       memset(as->urb->transfer_buffer, 0,
>>>> +                                       uurb->buffer_length);
>>>>        }
>>>>        as->urb->dev = ps->dev;
>>>>        as->urb->pipe = (uurb->type << 30) |
>>>> @@ -1312,10 +1319,14 @@ static int processcompl(struct async *as
>>>>        void __user *addr = as->userurb;
>>>>        unsigned int i;
>>>>
>>>> -       if (as->userbuffer && urb->actual_length)
>>>> -               if (copy_to_user(as->userbuffer, urb->transfer_buffer,
>>>> -                                urb->actual_length))
>>>> +       if (as->userbuffer && urb->actual_length) {
>>>> +               if (urb->number_of_packets > 0)         /* Isochronous */
>>>> +                       i = urb->transfer_buffer_length;
>>>> +               else                                    /* Non-Isoc */
>>>> +                       i = urb->actual_length;
>>>> +               if (copy_to_user(as->userbuffer, urb->transfer_buffer, i))
>>>>                        goto err_out;
>>>> +       }
>>>>        if (put_user(as->status, &userurb->status))
>>>>                goto err_out;
>>>>        if (put_user(urb->actual_length, &userurb->actual_length))
>>>>
>>>> It would be nice if this patch could go into the ubuntu lucid kernel
>>>> as soon as possible.
>>>>
>>>> Thanks,
>>>> Markus
>>> -- Chase
>>>
>> Well it seems to come from Alan Stern and be cc'ed to stable. So it should/would
>> come from there. But I have not seen it in the queue, yet. But it is in upstream:
>>
>> commit 7152b592593b9d48b33f8997b1dfd6df9143f7ec
>> Author: Alan Stern <stern at rowland.harvard.edu>
>> Date:   Sat Mar 6 15:04:03 2010 -0500
>>
>>    USB: fix usbfs regression
> 
> Ahh, I didn't realize Alan is the maintainer of the code. I'll leave
> it up to you, Stefan, to determine how to handle this.
> 
> -- Chase

As this patch is upstream and has been cc'ed to stable too, I would ACK to
cherry-pick the upstream patch (attached for simplicity)

Stefan

-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0001-USB-fix-usbfs-regression.patch
Type: text/x-diff
Size: 2131 bytes
Desc: not available
URL: <https://lists.ubuntu.com/archives/kernel-team/attachments/20100329/3f9a685b/attachment.patch>