On Thu, May 19, 2016 at 05:19:00PM -0400, Valdis Kletnieks wrote:
> UBSAN throws a complaint:
>
> [ 2.418579] UBSAN: Undefined behaviour in
> drivers/usb/host/ehci-hub.c:877:47
> [ 2.418582] index -1 is out of range for type 'u32 [1]'
>
> though it's only on the hostpc[] part, not on the port_status[] on the
> previous line which has the same exact index calculation. The root cause is
> that the first declaration is port_status[0], which uses a GCC extension and
> UBSAN is smart enough to realize the programmer is doing something
> intentionally odd.
>
> However, the problematic declaration is hostpc[1], which doesn't have
> the "I know what I'm doing" semantics of [0]. Change the declaration to
> match.
>
> Signed-Off-By: Valdis Kletnieks <valdis.kletni...@vt.edu>
>
> --- a/include/linux/usb/ehci_def.h 2015-01-06 01:04:24.342436706 -0500
> +++ b/include/linux/usb/ehci_def.h 2016-05-19 13:57:20.869304540 -0400
> @@ -180,11 +180,11 @@ struct ehci_regs {
> * PORTSCx
> */
> /* HOSTPC: offset 0x84 */
> - u32 hostpc[1]; /* HOSTPC extension */
> + u32 hostpc[0]; /* HOSTPC extension */
> #define HOSTPC_PHCD (1<<22) /* Phy clock disable */
> #define HOSTPC_PSPD (3<<25) /* Port speed detection */
Hm, this is odd, you really do want hostpc to be 1 u32 value, don't make
it 0 please. If you walk off the end of hostpc, well, let's fix that
properly.
And are you sure this is needed? Is this a different issue from the
other long thread right now that we finally got a patch for?
thanks,
greg k-h
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