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SubjectRe: [PATCH 1/1] USBHID: correct start/stop cycle
On Sat, 1 Nov 2008, Jiri Slaby wrote:

> `stop' left out usbhid->urb* pointers and so the next `start' thought
> it needs to allocate nothing and used the memory pointers previously
> pointed to. This led to memory corruption and device malfunction.
>
> Also don't forget to clear disconnect flag on start which was left set
> by the previous `stop'.
>
> Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
> ---
> drivers/hid/usbhid/hid-core.c | 8 ++++++++
> 1 files changed, 8 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
> index 18e5ddd..f0339ae 100644
> --- a/drivers/hid/usbhid/hid-core.c
> +++ b/drivers/hid/usbhid/hid-core.c
> @@ -781,6 +781,8 @@ static int usbhid_start(struct hid_device *hid)
> unsigned int n, insize = 0;
> int ret;
>
> + clear_bit(HID_DISCONNECTED, &usbhid->iofl);
> +
> usbhid->bufsize = HID_MIN_BUFFER_SIZE;
> hid_find_max_report(hid, HID_INPUT_REPORT, &usbhid->bufsize);
> hid_find_max_report(hid, HID_OUTPUT_REPORT, &usbhid->bufsize);
> @@ -888,6 +890,9 @@ fail:
> usb_free_urb(usbhid->urbin);
> usb_free_urb(usbhid->urbout);
> usb_free_urb(usbhid->urbctrl);
> + usbhid->urbin = NULL;
> + usbhid->urbout = NULL;
> + usbhid->urbctrl = NULL;
> hid_free_buffers(dev, hid);
> mutex_unlock(&usbhid->setup);
> return ret;
> @@ -924,6 +929,9 @@ static void usbhid_stop(struct hid_device *hid)
> usb_free_urb(usbhid->urbin);
> usb_free_urb(usbhid->urbctrl);
> usb_free_urb(usbhid->urbout);
> + usbhid->urbin = NULL; /* don't mess up next start */
> + usbhid->urbctrl = NULL;
> + usbhid->urbout = NULL;
>
> hid_free_buffers(hid_to_usb_dev(hid), hid);
> mutex_unlock(&usbhid->setup);

Jeroen, Helge,

could you please verify whether this patch fixes the corruption you were
experiencing?

[ I will be offline for the upcoming ~9 days, will push the fix upstream
then, if it is not picked up through different channels in the
meantime ]

Thanks!

--
Jiri Kosina
SUSE Labs


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