Re: 2.6.23 regression: accessing invalid mmap'ed memory from gdb causes unkillable spinning

Nick Piggin
2007-10-31T22:55:52Z

On Wed, Oct 31, 2007 at 08:59:41AM -0700, Linus Torvalds wrote:
>
>
> On Wed, 31 Oct 2007, Nick Piggin wrote:
> >
> > Well the patch is right, in the context of the regression I introduced
> > (and so it should probably go into 2.6.23).
>
> Yeah, it probably is fine for -stable.
>
> And if mine (which actually changes behaviour, in that it makes ptrace get
> an access error) causes regressions, I guess we'll have to use that
> compatible-with-old-behaviour one for 2.6.24 too.
>
> But I just rebooted and tested - the cleaned-up patch does seem to work
> fine, and I get "Cannot access memory at address <xyz>" rather than any
> reported problem.
>
> So I think I'll commit my version asap, and see if anybody reports that
> they have a situation where they use ptrace() and expect zero back from a
> shared mapping past the end.. And if there are issues, we can switch back
> to the old broken behaviour with your patch,

No that would be great. Fingers crossed it won't cause any problems.

Thanks, all.