Re: [PATCH] usb: gadget: f_fs: get the correct address of comp_desc

[wlf]

Hi Jack,

å 2018å02æ06æ 02:17, Jack Pham åé:
> Hi William,
>
> On Mon, Feb 05, 2018 at 07:33:38PM +0800, William Wu wrote:
> > Refer to the USB 3.0 spec '9.6.7 SuperSpeed Endpoint Companion',
> > the companion descriptor follows the standard endpoint descriptor.
> > This descriptor is only defined for SuperSpeed endpoints. The
> > f_fs driver gets the address of the companion descriptor via
> > 'ds + USB_DT_ENDPOINT_SIZE', and actually, the ds variable is
> > a pointer to the struct usb_endpoint_descriptor, so the offset
> > of the companion descriptor which we get is USB_DT_ENDPOINT_SIZE *
> > sizeof(struct usb_endpoint_descriptor), the wrong offset is 63
> > bytes. This cause out-of-bound with the following error log if
> > CONFIG_KASAN and CONFIG_SLUB_DEBUG is enabled on Rockchip RK3399
> > Evaluation Board.
> >
> > android_work: sent uevent USB_STATE=CONNECTED
> > configfs-gadget gadget: super-speed config #1: b
> > ==================================================================
> > BUG: KASAN: slab-out-of-bounds in ffs_func_set_alt+0x230/0x398
> > Read of size 1 at addr ffffffc0ce2d0b10 by task irq/224-dwc3/364
> > Memory state around the buggy address:
> >   ffffffc0ce2d0a00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> >   ffffffc0ce2d0a80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> >   >ffffffc0ce2d0b00: 00 04 fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> >                           ^
> >   ffffffc0ce2d0b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> >   ffffffc0ce2d0c00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> > ==================================================================
> > Disabling lock debugging due to kernel taint
> > android_work: sent uevent USB_STATE=CONFIGURED
> >
> > This patch adds struct usb_endpoint_descriptor * -> u8 * type conversion
> > for ds variable, then we can get the correct address of comp_desc
> > with offset USB_DT_ENDPOINT_SIZE bytes.
> >
> > Signed-off-by: William Wu <william.wu@xxxxxxxxxxxxxx>
> > ---
> >   drivers/usb/gadget/function/f_fs.c | 4 ++--
> >   1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
> > index 6756472..f13ead0 100644
> > --- a/drivers/usb/gadget/function/f_fs.c
> > +++ b/drivers/usb/gadget/function/f_fs.c
> > @@ -1882,8 +1882,8 @@ static int ffs_func_eps_enable(struct ffs_function *func)
> >   		ep->ep->desc = ds;
> >   
> >   		if (needs_comp_desc) {
> > -			comp_desc = (struct usb_ss_ep_comp_descriptor *)(ds +
> > -					USB_DT_ENDPOINT_SIZE);
> > +			comp_desc = (struct usb_ss_ep_comp_descriptor *)
> > +				     ((u8 *)ds + USB_DT_ENDPOINT_SIZE);
> >   			ep->ep->maxburst = comp_desc->bMaxBurst + 1;
> >   			ep->ep->comp_desc = comp_desc;
> >   		}
> Please see my alternative fix for this. I proposed changing this
> function to use config_ep_by_speed() instead.
>
> https://www.spinics.net/lists/linux-usb/msg165149.html
Thanks for your great job!
ÂYour patch seems good, I will test your patch on my RK3399-EVB board.

William

> Jack