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: <20151105055624.GA29116@cmpxchg.org>
Date:	Thu, 5 Nov 2015 00:56:24 -0500
From:	Johannes Weiner <hannes@...xchg.org>
To:	Tejun Heo <tj@...nel.org>
Cc:	Li Zefan <lizefan@...wei.com>, cgroups@...r.kernel.org,
	linux-kernel@...r.kernel.org, James Sedgwick <jsedgwick@...com>,
	kernel-team@...com
Subject: Re: [PATCH cgroup/for-4.4-fixes] cgroup: fix cftype->file_offset
 handling

On Thu, Nov 05, 2015 at 12:12:24AM -0500, Tejun Heo wrote:
> 6f60eade2433 ("cgroup: generalize obtaining the handles of and
> notifying cgroup files") introduced cftype->file_offset so that the
> handles for per-css file instances can be recorded.  These handles
> then can be used, for example, to generate file modified
> notifications.
> 
> Unfortunately, it made the wrong assumption that files are created
> once for a given css and removed on its destruction.  Due to the
> dependencies among subsystems, a css may be hidden from userland and
> then later shown again.  This is implemented by removing and
> re-creating the affected files, so the associated kernfs_node for a
> given cgroup file may change over time.  This incorrect assumption led
> to the corruption of css->files lists.
>
> Reimplement cftype->file_offset handling so that cgroup_file->kn is
> protected by a lock and updated as files are created and destroyed.
> This also makes keeping them on per-cgroup list unnecessary.
> 
> Signed-off-by: Tejun Heo <tj@...nel.org>
> Reported-by: James Sedgwick <jsedgwick@...com>
> Fixes: 6f60eade2433 ("cgroup: generalize obtaining the handles of and notifying cgroup files")

Kudos to whoever debugged this.

Acked-by: Johannes Weiner <hannes@...xchg.org>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ