Re: [PATCH v3] HID: keep dev_rdesc unmodified and use it for comparisons

[Randy Levensalor <randyl@xxxxxx>]

On 12/31/1969 05:00 PM, wrote:
> usbhid's hid_post_reset checks the report descriptor currently 
> returned by the
> device against a descriptor that may have been modified by a driver's
> report_fixup method. That leaves some devices nonfunctional after a 
> resume, with
> a "reset_resume error 1" reported. This patch checks the new 
> descriptor against
> the unmodified dev_rdesc instead and uses the original, instead of 
> modified,
> report size.
Thanks for the patch.  I had the same problem with a Logitech mouse and 
this fixed it.

Tested-by: Randy Levensalor <randyl@xxxxxx>

> BugLink: http://bugs.launchpad.net/bugs/1049623
> Signed-off-by: Kevin Daughtridge &lt;kevin@xxxxxxxx&gt;
> ---
>  drivers/hid/hid-core.c        |   16 +++++++++++++---
>  drivers/hid/usbhid/hid-core.c |    6 +++---
>  2 files changed, 16 insertions(+), 6 deletions(-)
>
> Changed in this version: added a temporary buffer to work around 
> report_fixup
> inconsistencies; using dev_rsize instead of rsize to allocate and read new
> descriptor.
>
> diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
> index 8bcd168..5de3bb3 100644
> --- a/drivers/hid/hid-core.c
> +++ b/drivers/hid/hid-core.c
> @@ -757,6 +757,7 @@ int hid_open_report(struct hid_device *device)
>      struct hid_item item;
>      unsigned int size;
>      __u8 *start;
> +    __u8 *buf;
>      __u8 *end;
>      int ret;
>      static int (*dispatch_type[])(struct hid_parser *parser,
> @@ -775,12 +776,21 @@ int hid_open_report(struct hid_device *device)
>          return -ENODEV;
>      size = device-&gt;dev_rsize;
>
> +    buf = kmemdup(start, size, GFP_KERNEL);
> +    if (buf == NULL)
> +        return -ENOMEM;
> +
>      if (device-&gt;driver-&gt;report_fixup)
> -        start = device-&gt;driver-&gt;report_fixup(device, start, 
> &amp;size);
> +        start = device-&gt;driver-&gt;report_fixup(device, buf, 
> &amp;size);
> +    else
> +        start = buf;
>
> -    device-&gt;rdesc = kmemdup(start, size, GFP_KERNEL);
> -    if (device-&gt;rdesc == NULL)
> +    start = kmemdup(start, size, GFP_KERNEL);
> +    kfree(buf);
> +    if (start == NULL)
>          return -ENOMEM;
> +
> +    device-&gt;rdesc = start;
>      device-&gt;rsize = size;
>
>      parser = vzalloc(sizeof(struct hid_parser));
> diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
> index dedd8e4..8e0c4bf94 100644
> --- a/drivers/hid/usbhid/hid-core.c
> +++ b/drivers/hid/usbhid/hid-core.c
> @@ -1415,20 +1415,20 @@ static int hid_post_reset(struct usb_interface 
> *intf)
>       * configuration descriptors passed, we already know that
>       * the size of the HID report descriptor has not changed.
>       */
> -    rdesc = kmalloc(hid-&gt;rsize, GFP_KERNEL);
> +    rdesc = kmalloc(hid-&gt;dev_rsize, GFP_KERNEL);
>      if (!rdesc) {
>          dbg_hid("couldn't allocate rdesc memory (post_reset)\n");
>          return 1;
>      }
>      status = hid_get_class_descriptor(dev,
>                  interface-&gt;desc.bInterfaceNumber,
> -                HID_DT_REPORT, rdesc, hid-&gt;rsize);
> +                HID_DT_REPORT, rdesc, hid-&gt;dev_rsize);
>      if (status &lt; 0) {
>          dbg_hid("reading report descriptor failed (post_reset)\n");
>          kfree(rdesc);
>          return 1;
>      }
> -    status = memcmp(rdesc, hid-&gt;rdesc, hid-&gt;rsize);
> +    status = memcmp(rdesc, hid-&gt;dev_rdesc, hid-&gt;dev_rsize);
>      kfree(rdesc);
>      if (status != 0) {
>          dbg_hid("report descriptor changed\n");
> --
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