linux-kernel - Re: [PATCH] virtio-console: avoid DMA from stack

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Date:   Wed, 1 Mar 2017 23:25:14 +0200
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Omar Sandoval <osandov@...ndov.com>
Cc:     Amit Shah <amit@...nel.org>,
        virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, kernel-team@...com
Subject: Re: [PATCH] virtio-console: avoid DMA from stack

On Wed, Mar 01, 2017 at 12:01:10PM -0800, Omar Sandoval wrote:
> On Wed, Feb 01, 2017 at 07:17:12PM +0530, Amit Shah wrote:
> > On (Wed) 01 Feb 2017 [00:02:27], Omar Sandoval wrote:
> > > From: Omar Sandoval <osandov@...com>
> > > 
> > > put_chars() stuffs the buffer it gets into an sg, but that buffer may be
> > > on the stack. This breaks with CONFIG_VMAP_STACK=y (for me, it
> > > manifested as printks getting turned into NUL bytes).
> > 
> > Seems reasonable.  I wonder since all implementations of hvc do a
> > memcpy, if we can abstract it - but that'll need some work.
> > 
> > Reviewed-by: Amit Shah <amit.shah@...hat.com>
> > 
> > Michael, please add to the virtio queue.
> > 
> > 		Amit
> 
> Hi, Michael,
> 
> I don't see this in Linus' master or in your git tree, is it going to go
> in for -rc1?
> 
> Thanks.

Yes.