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From: "Michael S. Tsirkin" <mst@redhat.com>
To: Peter Xu <peterx@redhat.com>
Cc: "Fabiano Rosas" <farosas@suse.de>,
	qemu-devel@nongnu.org, "Stefano Garzarella" <sgarzare@redhat.com>,
	김승중 <seungjung0711@gmail.com>,
	"Alexandr Moshkov" <dtalexundeer@yandex-team.ru>
Subject: Re: [PATCH] vhost/migration: Fix incorrect size used in inflight->addr in VMSD
Date: Wed, 29 Jul 2026 14:57:57 -0400	[thread overview]
Message-ID: <20260729145247-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <amo86cXLNE2uV6Ge@x1.local>

On Wed, Jul 29, 2026 at 01:48:25PM -0400, Peter Xu wrote:
> So to me, it's much simpler we say migration stream must be
> trusted, and I expect dest QEMU can allocate any buffer it needs, until it
> eats the whole system memory.  I really don't see much real risk..

It's not risk due to migration, specifically. But making qemu
drink up terabytes from the guest would be problematic, right?

Putting qemu in a cgroup with restricted total memory
would be one way to prevent this class of security issue,
and a robust one.

But that, in turn, is impossible if qemu insists on allocating
unlimited memory at the drop of a hat.

However, migration is hardly the worst offender here, and I am
not at all sure we need to start with it if we even want
to address this limitation.

-- 
MST



  reply	other threads:[~2026-07-29 18:58 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-28 15:39 [PATCH] vhost/migration: Fix incorrect size used in inflight->addr in VMSD Peter Xu
2026-07-28 20:57 ` Fabiano Rosas
2026-07-29 14:00   ` Peter Xu
2026-07-29 14:25     ` Michael S. Tsirkin
2026-07-29 14:27     ` Fabiano Rosas
2026-07-29 15:44       ` Peter Xu
2026-07-29 16:13         ` Fabiano Rosas
2026-07-29 17:40           ` Peter Xu
2026-07-29 17:48           ` Peter Xu
2026-07-29 18:57             ` Michael S. Tsirkin [this message]
2026-07-29 19:27               ` Peter Xu
2026-07-28 23:17 ` Michael S. Tsirkin
2026-07-29  7:25 ` Alexandr Moshkov
2026-07-29  8:49   ` Michael S. Tsirkin
2026-07-29 14:16     ` Peter Xu

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