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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CA+55aFxVG4xJ2AWpuo5fHPvkCTB6eAgogQ0UoJuQHo=MsXRb1w@mail.gmail.com>
Date:   Tue, 1 Aug 2017 10:53:17 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     "davej@...emonkey.org.uk" <davej@...emonkey.org.uk>,
        Trond Myklebust <trondmy@...marydata.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "bfields@...ldses.org" <bfields@...ldses.org>,
        "linux-nfs@...r.kernel.org" <linux-nfs@...r.kernel.org>,
        "schumaker.anna@...il.com" <schumaker.anna@...il.com>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>
Subject: Re: [GIT PULL] Please pull NFS client changes for Linux 4.13

On Tue, Aug 1, 2017 at 10:20 AM, Linus Torvalds
<torvalds@...ux-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