Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> writes:
> On Sun, 21 Aug 2016, Jiri Slaby wrote:
>
>> Cc: proper lists.
>>
>> ep->desc.bInterval seems to be 0 here.
>>
>> On 08/21/2016, 12:42 PM, Vittorio Zecca wrote:
>> > I am not sure this is the right place so please bear with me...
>> > From Vittorio Zecca
>> >
>> > After compiling kernel 4.7.2 with ubsan I got the following messages
>> > at boot time:
>> >
>> > (devio.c:1713 is "as->urb->interval = 1 << min(15, ep->desc.bInterval - 1);")
>> >
>> > [ +0.354486] ================================================================================
>> > [ +0.000008] UBSAN: Undefined behaviour in
>> > /home/vitti/1tb/vitti/rpmbuild/SOURCES/linux-4.7.2/drivers/usb/core/devio.c:1713:25
>> > [ +0.000004] shift exponent -1 is negative
>
> As far as I can see, this isn't possible. The usb_parse_endpoint()
> routine in drivers/usb/core/config.c is supposed to guarantee that
> ep->desc.bInterval is never 0.
That is if it is an ISO endpoint, right?
Maybe I misunderstand something fundamental, but the "||" strikes me as
odd here:
as->urb->stream_id = stream_id;
if (uurb->type == USBDEVFS_URB_TYPE_ISO ||
ps->dev->speed == USB_SPEED_HIGH)
as->urb->interval = 1 << min(15, ep->desc.bInterval - 1);
else
as->urb->interval = ep->desc.bInterval;
as->urb->context = as;
Typo?
Bjørn
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