Re: [GIT PULL] Please pull NFS client changes for Linux 4.13

From: Linus Torvalds
Date: Tue Aug 01 2017 - 13:53:25 EST

On Tue, Aug 1, 2017 at 10:20 AM, Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> So I think the 'pathname' part may actually be entirely a red herring,
> and it's the underlying access itself that just picks up a random
> pointer from a stack that now contains something different. And KASAN
> didn't notice the stale stack access itself, because the stack slot is
> still valid - it's just no longer the original 'verifier' allocation.
> Or *something* like that.

I think the "something like that" is actually just reading the
cdata->args.verifier->data pointer itself, and it *is* the stack
access - but the stack page has been free'd (because of the same fatal
signal that interrupted the rpc_wait_for_completion_task() call), and
then re-allocated (and free'd again) as a pathname page.


Regardless, my patch still looks conceptually correct, even if it
might have bugs due to total lack of testing.