Re: UBSAN: Undefined behaviour in drivers/usb/core/devio.c:1517:25

From: Alan Stern
Date: Tue Jan 26 2016 - 10:25:46 EST


On Tue, 26 Jan 2016, Chris Bainbridge wrote:

> Booting 4.5.0-rc1 with new UBSAN checker enabled:
>
> [ 4.556968] ================================================================================
> [ 4.556972] UBSAN: Undefined behaviour in drivers/usb/core/devio.c:1517:25
> [ 4.556975] shift exponent -1 is negative

Does a left shift by a negative amount matter if the result isn't used?

Alan Stern