Hi Mathias,
On Tue, 19 Dec 2017 11:14:42 +0200
Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> wrote:
> USB 3.1 devices are not detected as 3.1 capable since 4.15-rc3 due to a
> off by one in commit 81cf4a45360f ("USB: core: Add type-specific length
> check of BOS descriptors")
>
> It uses USB_DT_USB_SSP_CAP_SIZE() to get SSP capability size which takes
> the zero based SSAC as argument, not the actual count of sublink speed
> attributes.
>
> USB3 spec 9.6.2.5 says "The number of Sublink Speed Attributes = SSAC + 1."
>
> The type-specific length check patch was added to stable and needs to be
> fixed there as well
>
> Fixes: 81cf4a45360f ("USB: core: Add type-specific length check of BOS descriptors")
> Cc: linux-stable <stable@xxxxxxxxxxxxxxx>
> CC: Masakazu Mokuno <masakazu.mokuno@xxxxxxxxx>
> Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
> ---
> drivers/usb/core/config.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c
> index 78e92d2..c821b4b 100644
> --- a/drivers/usb/core/config.c
> +++ b/drivers/usb/core/config.c
> @@ -1007,7 +1007,7 @@ int usb_get_bos_descriptor(struct usb_device *dev)
> case USB_SSP_CAP_TYPE:
> ssp_cap = (struct usb_ssp_cap_descriptor *)buffer;
> ssac = (le32_to_cpu(ssp_cap->bmAttributes) &
> - USB_SSP_SUBLINK_SPEED_ATTRIBS) + 1;
> + USB_SSP_SUBLINK_SPEED_ATTRIBS);
> if (length >= USB_DT_USB_SSP_CAP_SIZE(ssac))
> dev->bos->ssp_cap = ssp_cap;
> break;
> --
> 2.7.4
Thanks for the fix. I got confused the meaning of USB_DT_USB_SSP_CAP_SIZE()
just as you described. The sizeof(struct usb_ssp_cap_descriptor) is 16,
but I did not noticed it included one SSAC.
There's another place that wrongly uses USB_DT_USB_SSP_CAP_SIZE() in my
previous patch. It should be fixed also. I'll make the patch.
--
Masakazu Mokuno
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