From: Andrew Cooper <Andrew.Cooper3@citrix.com>
To: Jan Beulich <jbeulich@suse.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"x86@kernel.org" <x86@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Juergen Gross <jgross@suse.com>,
"Rafael J. Wysocki" <rafael@kernel.org>,
xen-devel <xen-devel@lists.xenproject.org>,
Roger Pau Monne <roger.pau@citrix.com>,
Peter Zijlstra <peterz@infradead.org>,
Joan Bruguera <joanbrugueram@gmail.com>
Subject: Re: Wake-up from suspend to RAM broken under `retbleed=stuff`
Date: Wed, 11 Jan 2023 22:06:56 +0000 [thread overview]
Message-ID: <cfe514f9-bf6c-292d-a481-48614aeb9dd6@citrix.com> (raw)
In-Reply-To: <f2c151af-b3ba-69e6-2878-3256971f5a9d@suse.com>
On 11/01/2023 11:45 am, Jan Beulich wrote:
> On 11.01.2023 12:39, Andrew Cooper wrote:
>> The bigger issue with stuff accounting is that nothing AFAICT accounts
>> for the fact that any hypercall potentially empties the RSB in otherwise
>> synchronous program flow.
> But that's not just at hypercall boundaries, but effectively anywhere
> (i.e. whenever the hypervisor decides to de-schedule the vCPU)?
Correct, but it's only the RET instructions that reliably underflow the
RSB which can be usefully attacked.
The %rip at which Xen decides to de-schedule a vCPU are random from the
point of view of an attacker.
~Andrew
next prev parent reply other threads:[~2023-01-11 22:08 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-08 3:07 Joan Bruguera
2023-01-08 11:33 ` Borislav Petkov
2023-01-08 17:11 ` Joan Bruguera
2023-01-08 21:27 ` Borislav Petkov
2023-01-08 22:27 ` Joan Bruguera
2023-01-09 4:05 ` Joan Bruguera
2023-01-11 11:20 ` Peter Zijlstra
2023-01-11 11:39 ` Andrew Cooper
2023-01-11 11:45 ` Jan Beulich
2023-01-11 22:06 ` Andrew Cooper [this message]
2023-01-11 11:52 ` Juergen Gross
2023-01-11 12:59 ` Peter Zijlstra
2023-01-11 17:56 ` Rafael J. Wysocki
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