linux-kernel - Re: [PATCH] audit,io_uring: io_uring openat triggers audit reference count underflow

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Message-ID: <CAHC9VhTQFyyE59A3WG3Z0xkP6m31h1M0bvS=yihE7ukpUiDMug@mail.gmail.com>
Date:   Fri, 13 Oct 2023 11:56:08 -0400
From:   Paul Moore <paul@...l-moore.com>
To:     Christian Brauner <brauner@...nel.org>
Cc:     Dan Clash <daclash@...ux.microsoft.com>,
        linux-kernel@...r.kernel.org, axboe@...nel.dk,
        linux-fsdevel@...r.kernel.org, dan.clash@...rosoft.com,
        audit@...r.kernel.org, io-uring@...r.kernel.org
Subject: Re: [PATCH] audit,io_uring: io_uring openat triggers audit reference
 count underflow

On Fri, Oct 13, 2023 at 11:44 AM Christian Brauner <brauner@...nel.org> wrote:
>
> On Thu, 12 Oct 2023 14:55:18 -0700, Dan Clash wrote:
> > An io_uring openat operation can update an audit reference count
> > from multiple threads resulting in the call trace below.
> >
> > A call to io_uring_submit() with a single openat op with a flag of
> > IOSQE_ASYNC results in the following reference count updates.
> >
> > These first part of the system call performs two increments that do not race.
> >
> > [...]
>
> Picking this up as is. Let me know if this needs another tree.

Whoa.  A couple of things:

* Please don't merge patches into an upstream tree if all of the
affected subsystems haven't ACK'd the patch.  I know you've got your
boilerplate below about ACKs *after* the merge, which is fine, but I
find it breaks decorum a bit to merge patches without an explicit ACK
or even just a "looks good to me" from all of the relevant subsystems.
Of course there are exceptions for important patches that are rotting
on the mailing lists, but I don't believe that to be the case here.

* You didn't mention if you've marked this for stable or if you're
going to send this up to Linus now or wait for the merge window.  At a
minimum this should be marked for stable, and I believe it should also
be sent up to Linus prior to the v6.6 release; I'm guessing that is
what you're planning to do, but you didn't mention it here.

Regardless, as I mentioned in my last email (I think our last emails
raced a bit), I'm okay with this change, please add my ACK.

Acked-by: Paul Moore <paul@...l-moore.com>

> Applied to the vfs.misc branch of the vfs/vfs.git tree.
> Patches in the vfs.misc branch should appear in linux-next soon.
>
> Please report any outstanding bugs that were missed during review in a
> new review to the original patch series allowing us to drop it.
>
> It's encouraged to provide Acked-bys and Reviewed-bys even though the
> patch has now been applied. If possible patch trailers will be updated.
>
> Note that commit hashes shown below are subject to change due to rebase,
> trailer updates or similar. If in doubt, please check the listed branch.
>
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
> branch: vfs.misc
>
> [1/1] audit,io_uring: io_uring openat triggers audit reference count underflow
>       https://git.kernel.org/vfs/vfs/c/c6f4350ced79

-- 
paul-moore.com