netdev - Re: [PATCH 1/5] virtio-net: fix overflow inside virtnet_rq

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Message-ID: <20241019123220-mutt-send-email-mst@kernel.org>
Date: Sat, 19 Oct 2024 12:34:17 -0400
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Paolo Abeni <pabeni@...hat.com>
Cc: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>, netdev@...r.kernel.org,
	Jason Wang <jasowang@...hat.com>,
	Eugenio Pérez <eperezma@...hat.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, virtualization@...ts.linux.dev,
	Si-Wei Liu <si-wei.liu@...cle.com>
Subject: Re: [PATCH 1/5] virtio-net: fix overflow inside virtnet_rq_alloc

On Thu, Oct 17, 2024 at 03:42:59PM +0200, Paolo Abeni wrote:
> 
> 
> On 10/14/24 05:12, Xuan Zhuo wrote:
> > When the frag just got a page, then may lead to regression on VM.
> > Specially if the sysctl net.core.high_order_alloc_disable value is 1,
> > then the frag always get a page when do refill.
> > 
> > Which could see reliable crashes or scp failure (scp a file 100M in size
> > to VM):
> > 
> > The issue is that the virtnet_rq_dma takes up 16 bytes at the beginning
> > of a new frag. When the frag size is larger than PAGE_SIZE,
> > everything is fine. However, if the frag is only one page and the
> > total size of the buffer and virtnet_rq_dma is larger than one page, an
> > overflow may occur.
> > 
> > Here, when the frag size is not enough, we reduce the buffer len to fix
> > this problem.
> > 
> > Fixes: f9dac92ba908 ("virtio_ring: enable premapped mode whatever use_dma_api")
> > Reported-by: "Si-Wei Liu" <si-wei.liu@...cle.com>
> > Signed-off-by: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
> 
> This looks like a fix that should target the net tree, but the following
> patches looks like net-next material. Any special reason to bundle them
> together?
> 
> Also, please explicitly include the the target tree in the subj on next
> submissions, thanks!
> 
> Paolo

The issue is that net-next is not rebased on net, so if patches 2-5 land
in next and 1 only in net, next will be broken. I think the simplest fix
is just to have 1 on net-next, backport it to net too, and git will
figure it out. Right?

-- 
MST