From: Andrew Morton <akpm@linux-foundation.org>
To: Eric Paris <eparis@redhat.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH] inotify: race use after free/double free in inotify inode marks
Date: Wed, 12 May 2010 20:16:31 -0400 [thread overview]
Message-ID: <20100512201631.a6955325.akpm@linux-foundation.org> (raw)
In-Reply-To: <1273680480-2550-1-git-send-email-eparis@redhat.com>
On Wed, 12 May 2010 12:08:00 -0400 Eric Paris <eparis@redhat.com> wrote:
> From: root <root@tyan-gt24-04.rhts.eng.bos.redhat.com>
hm.
> There is a race in the inotify add/rm watch code. A task can find and
> remove a mark which doesn't have all of it's references. This can
> result in a use after free/double free situation.
>
> Task A Task B
> ------------ -----------
> inotify_new_watch()
> allocate a mark (refcnt == 1)
> add it to the idr
> inotify_rm_watch()
> inotify_remove_from_idr()
> fsnotify_put_mark()
> refcnt hits 0, free
> take reference because we are on idr
> [at this point it is a use after free]
> [time goes on]
> refcnt may hit 0 again, double free
>
> The fix is to take the reference BEFORE the object can be found in the
> idr.
>
> Signed-off-by: Eric Paris <eparis@redhat.com>
The changelog has no "Cc: <stable@kernel.org>". I suspect it should
have that?
next prev parent reply other threads:[~2010-05-13 3:18 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-12 16:08 [PATCH] inotify: race use after free/double free in inotify inode marks Eric Paris
2010-05-13 0:16 ` Andrew Morton [this message]
2010-05-13 11:31 ` Eric Paris
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