On Tue, 16 Apr 2019 11:07:56 -0400, Alan Stern wrote: > On Tue, 16 Apr 2019, zhuyan (M) wrote: > > On Tue, 16 Apr 2019 at 11:45:45 +0200, Greg KH wrote: > > > On Tue, Apr 09, 2019 at 10:37:12PM +0800, zhuyan wrote: > > > > In function fhci_queue_urb, the divisor of expression > > > > (urb->transfer_buffer_length % usb_maxpacket(urb->dev, urb->pipe, > > > > usb_pipeout(urb->pipe))) may be zero. > > > > > > How can you hit that? > > > > > > > When it is zero, unexpected results may occur, so it is necessary > > > > to ensure that the divisor is not zero. > > > > > > > > Signed-off-by: zhuyan <zhuyan34@xxxxxxxxxx> > > > > > > I need a "Full" name here, not just a single name. Whatever you use to sign documents is good. > > > > > > thanks, > > > > > > greg k-h > > > > In function usb_maxpacket, when ep is NULL, its return value is 0. > > fhci_queue_urb() shouldn't use urb->pipe to compute the maxpacket size > anyway. It should use usb_endpoint_maxp(&urb->ep->desc). Currently, fhci_queue_urb(), call usb_maxpacket() multiple times to calculate the maxpacket size. The usb_maxpacket() will call usb_endpoint_maxp() to compute the maxpacket size. zhuyan > > Then, in function fhci_queue_urb, the divisor of expression > > (urb->transfer_buffer_length % usb_maxpacket(urb->dev, urb->pipe, > > usb_pipeout(urb->pipe))) is zero. It will lead to unpredictable results.
