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

From	Trond Myklebust <trondmy@primarydata.com>
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-19@gated-at.bofh.it> (permalink)
References	(6 earlier) <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> <u9JCx-74V-9@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On Tue, 2017-08-01 at 13:50 -0400, davej@codemonkey.org.uk wrote:
> On Tue, Aug 01, 2017 at 10:20:31AM -0700, Linus Torvalds 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.
>  > 
>  > None of this looks even remotely new, though - the code seems to
> go
>  > back to 2009. Have you just changed what you're testing to trigger
>  > these things?
> 
> No idea why it only just showed up, but it isn't 100% reproducable
> either.  A month or so ago I did disable the V4 code on the server
> completely (as I was using v3 everywhere else), so maybe I started
> hitting
> a fallback path somewhere.  *shrug*
> 

I would only expect you too see it if you interrupt the wait on the
asynchronous EXCHANGE_ID call (which would allow the RPC call to
continue while the caller stack is trashed). Prior to commit
8d89bd70bc939, that code path was fully synchronous, so there was no
issue with interrupting the call.

-- 
Trond Myklebust
Linux NFS client maintainer, PrimaryData
trond.myklebust@primarydata.com

Thread

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

csiph-web