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

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  Re: [PATCH] virtio-console: avoid DMA from stack Omar Sandoval <osandov@osandov.com> - 2017-03-01 21:20 +0100
    Re: [PATCH] virtio-console: avoid DMA from stack "Michael S. Tsirkin" <mst@redhat.com> - 2017-03-01 22:40 +0100

#1590610 — Re: [PATCH] virtio-console: avoid DMA from stack

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@fb.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@redhat.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.

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#1590637

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@fb.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@redhat.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.

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