On Sun, 8 Apr 2018 09:20:26 +0200 Takashi Iwai <ti...@suse.de> wrote:
> We've got a bug report indicating a kernel panic at booting on an
> x86-32 system, and it turned out to be the invalid resource assigned
> after PCI resource reallocation. __find_resource() first aligns the
> resource start address and resets the end address with start+size-1
> accordingly, then checks whether it's contained. Here the end address
> may overflow the integer, although resource_contains() still returns
> true because the function validates only start and end address. So
> this ends up with returning an invalid resource (start > end).
>
> There was already an attempt to cover such a problem in the commit
> 47ea91b4052d ("Resource: fix wrong resource window calculation"), but
> this case is an overseen one.
>
> This patch adds the validity check in resource_contains() to see
> whether the given resource has a valid range for avoiding the integer
> overflow problem.
>
> ...
>
> --- a/include/linux/ioport.h
> +++ b/include/linux/ioport.h
> @@ -212,6 +212,9 @@ static inline bool resource_contains(struct resource *r1,
> struct resource *r2)
> return false;
> if (r1->flags & IORESOURCE_UNSET || r2->flags & IORESOURCE_UNSET)
> return false;
> + /* sanity check whether it's a valid resource range */
> + if (r2->end < r2->start)
> + return false;
> return r1->start <= r2->start && r1->end >= r2->end;
> }
This doesn't look like the correct place to handle this? Clearly .end
< .start is an invalid state for a resource and we should never have
constructed such a thing in the first place? So adding a check at the
place where this resource was initially created seems to be the correct
fix?
