From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: Cyril Bur <cyrilbur@gmail.com>,
devicetree@vger.kernel.org, jassisinghbrar@gmail.com,
arnd@arndb.de, joel@jms.id.au, mark.rutland@arm.com,
robh+dt@kernel.org, openbmc@lists.ozlabs.org, andrew@aj.id.au,
xow@google.com, jk@ozlabs.org
Subject: Re: [PATCH 3/4] drivers/misc: Add ASpeed LPC control driver
Date: Thu, 12 Jan 2017 10:31:30 -0600 [thread overview]
Message-ID: <1484238690.2492.47.camel@kernel.crashing.org> (raw)
In-Reply-To: <20170112162619.GB10283@kroah.com>
On Thu, 2017-01-12 at 17:26 +0100, Greg KH wrote:
> I think, you can change things after access_ok() happens, there used to
> be bugs in that area a few years ago. I think we fixed them by moving
> the offending drivers to use copy_*() instead.
Ok, I'm surprised though, we still have a metric ton of code,
especially in filesystems, who do access_ok. Generally the idea here is
that the enforcement is done by the MMU normally via the permission in
the page tables. access_ok() is simply needed to make sure we access
the portion of the page tables representing user space, not kernel
space, and that is a pretty fixed dichotomy.
Anyway, this is academic, I agree that copy_to/from_... is nicer.
Cheers,
Ben.
WARNING: multiple messages have this Message-ID (diff)
From: Benjamin Herrenschmidt <benh-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>
To: Greg KH <gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>
Cc: Cyril Bur <cyrilbur-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
jassisinghbrar-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org,
arnd-r2nGTMty4D4@public.gmane.org,
joel-U3u1mxZcP9KHXe+LvDLADg@public.gmane.org,
mark.rutland-5wv7dgnIgG8@public.gmane.org,
robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
openbmc-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org,
andrew-zrmu5oMJ5Fs@public.gmane.org,
xow-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org,
jk-mnsaURCQ41sdnm+yROfE0A@public.gmane.org
Subject: Re: [PATCH 3/4] drivers/misc: Add ASpeed LPC control driver
Date: Thu, 12 Jan 2017 10:31:30 -0600 [thread overview]
Message-ID: <1484238690.2492.47.camel@kernel.crashing.org> (raw)
In-Reply-To: <20170112162619.GB10283-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>
On Thu, 2017-01-12 at 17:26 +0100, Greg KH wrote:
> I think, you can change things after access_ok() happens, there used to
> be bugs in that area a few years ago. I think we fixed them by moving
> the offending drivers to use copy_*() instead.
Ok, I'm surprised though, we still have a metric ton of code,
especially in filesystems, who do access_ok. Generally the idea here is
that the enforcement is done by the MMU normally via the permission in
the page tables. access_ok() is simply needed to make sure we access
the portion of the page tables representing user space, not kernel
space, and that is a pretty fixed dichotomy.
Anyway, this is academic, I agree that copy_to/from_... is nicer.
Cheers,
Ben.
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next prev parent reply other threads:[~2017-01-12 16:31 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-12 0:29 [PATCH 0/4] ASpeed mailbox and LPC control drivers Cyril Bur
2017-01-12 0:29 ` Cyril Bur
2017-01-12 0:29 ` [PATCH 1/4] Documentation: dt: mailbox: Add Aspeed ast2400/2500 bindings Cyril Bur
2017-01-12 0:29 ` Cyril Bur
2017-01-18 20:38 ` Rob Herring
2017-01-18 20:38 ` Rob Herring
2017-01-19 0:05 ` Cyril Bur
2017-01-19 0:05 ` Cyril Bur
2017-01-19 15:08 ` Benjamin Herrenschmidt
2017-01-19 15:08 ` Benjamin Herrenschmidt
2017-01-12 0:29 ` [PATCH 2/4] Documentation: dt: misc: Add Aspeed ast2400/2500 LPC Control bindings Cyril Bur
2017-01-12 0:29 ` Cyril Bur
2017-01-18 21:16 ` Rob Herring
2017-01-18 21:16 ` Rob Herring
2017-01-19 0:19 ` Cyril Bur
2017-01-19 0:19 ` Cyril Bur
2017-01-12 0:29 ` [PATCH 3/4] drivers/misc: Add ASpeed LPC control driver Cyril Bur
2017-01-12 0:29 ` Cyril Bur
2017-01-12 7:43 ` Greg KH
2017-01-12 7:43 ` Greg KH
2017-01-12 15:36 ` Benjamin Herrenschmidt
2017-01-12 15:36 ` Benjamin Herrenschmidt
2017-01-12 7:47 ` Greg KH
2017-01-12 7:47 ` Greg KH
2017-01-12 10:16 ` Cyril Bur
2017-01-12 10:16 ` Cyril Bur
2017-01-12 10:30 ` Greg KH
2017-01-12 10:30 ` Greg KH
2017-01-12 15:27 ` Benjamin Herrenschmidt
2017-01-12 15:27 ` Benjamin Herrenschmidt
2017-01-12 16:00 ` Greg KH
2017-01-12 16:00 ` Greg KH
2017-01-12 16:07 ` Benjamin Herrenschmidt
2017-01-12 16:07 ` Benjamin Herrenschmidt
2017-01-12 16:26 ` Greg KH
2017-01-12 16:26 ` Greg KH
2017-01-12 16:31 ` Benjamin Herrenschmidt [this message]
2017-01-12 16:31 ` Benjamin Herrenschmidt
2017-01-12 15:35 ` Benjamin Herrenschmidt
2017-01-12 15:35 ` Benjamin Herrenschmidt
2017-01-12 16:27 ` Greg KH
2017-01-12 16:27 ` Greg KH
2017-01-12 16:29 ` Benjamin Herrenschmidt
2017-01-12 16:29 ` Benjamin Herrenschmidt
2017-01-12 17:27 ` Greg KH
2017-01-12 17:27 ` Greg KH
2017-01-12 0:29 ` [PATCH 4/4] drivers/mailbox: Add ASpeed mailbox driver Cyril Bur
2017-01-12 0:29 ` Cyril Bur
2017-02-07 5:40 ` Joel Stanley
2017-02-07 5:40 ` Joel Stanley
2017-02-07 5:44 ` Benjamin Herrenschmidt
2017-02-07 5:44 ` Benjamin Herrenschmidt
2017-02-07 22:57 ` Cyril Bur
2017-02-07 22:57 ` Cyril Bur
2017-02-07 22:59 ` Joel Stanley
2017-02-07 22:59 ` Joel Stanley
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