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

From	Linus Torvalds <torvalds@linux-foundation.org>
Newsgroups	linux.kernel
Subject	Re: [GIT PULL] Please pull NFS client changes for Linux 4.13
Date	2017-08-01 20:00 +0200
Message-ID	<u9JCy-74V-37@gated-at.bofh.it> (permalink)
References	(5 earlier) <u4jz4-zE-11@gated-at.bofh.it> <u9l7b-82B-15@gated-at.bofh.it> <u9y4p-7Cw-1@gated-at.bofh.it> <u9HKq-5Q8-29@gated-at.bofh.it> <u9J9x-6UE-23@gated-at.bofh.it>
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On Tue, Aug 1, 2017 at 10:20 AM, Linus Torvalds
<torvalds@linux-foundation.org> 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.

Maybe.

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

                    Linus

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Re: [GIT PULL] Please pull NFS client changes for Linux 4.13 "davej@codemonkey.org.uk" <davej@codemonkey.org.uk> - 2017-07-31 17:50 +0200
  Re: [GIT PULL] Please pull NFS client changes for Linux 4.13 Linus Torvalds <torvalds@linux-foundation.org> - 2017-08-01 07:40 +0200
    Re: [GIT PULL] Please pull NFS client changes for Linux 4.13 "davej@codemonkey.org.uk" <davej@codemonkey.org.uk> - 2017-08-01 18:00 +0200
      Re: [GIT PULL] Please pull NFS client changes for Linux 4.13 Linus Torvalds <torvalds@linux-foundation.org> - 2017-08-01 19:30 +0200
        Re: [GIT PULL] Please pull NFS client changes for Linux 4.13 Trond Myklebust <trondmy@primarydata.com> - 2017-08-01 19:40 +0200
        Re: [GIT PULL] Please pull NFS client changes for Linux 4.13 "davej@codemonkey.org.uk" <davej@codemonkey.org.uk> - 2017-08-01 20:00 +0200
          Re: [GIT PULL] Please pull NFS client changes for Linux 4.13 Trond Myklebust <trondmy@primarydata.com> - 2017-08-01 20:00 +0200
        Re: [GIT PULL] Please pull NFS client changes for Linux 4.13 Linus Torvalds <torvalds@linux-foundation.org> - 2017-08-01 20:00 +0200

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