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

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Message-ID: <20170201134712.GA7935@amit-lp.rh>
Date:   Wed, 1 Feb 2017 19:17:12 +0530
From:   Amit Shah <amit.shah@...hat.com>
To:     Omar Sandoval <osandov@...ndov.com>
Cc:     virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, kernel-team@...com,
        "Michael S. Tsirkin" <mst@...hat.com>
Subject: Re: [PATCH] virtio-console: avoid DMA from stack

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