Messages in this thread | | | Date | Mon, 22 Aug 2016 13:43:30 -0400 (EDT) | From | Alan Stern <> | Subject | Re: UBSAN: Undefined behaviour in linux-4.7.2/drivers/usb/core/devio.c:1713:25 |
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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.
More information from Vittorio would be helpful. For example, what shows up in /sys/kernel/debug/usb/devices (after mounting a debugfs filesystem on /sys/kernel/debug)?
Alan Stern
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