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From: Jan Beulich <jbeulich@suse.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: "Roger Pau Monné" <roger.pau@citrix.com>, "Wei Liu" <wl@xen.org>,
	Xen-devel <xen-devel@lists.xenproject.org>
Subject: Re: [PATCH] x86/spec-ctrl: Use IST RSB protection for !SVM systems
Date: Fri, 5 Aug 2022 12:49:40 +0200	[thread overview]
Message-ID: <ab786545-6cd8-ab89-7b94-0fa3cda464ae@suse.com> (raw)
In-Reply-To: <20220805103814.23032-1-andrew.cooper3@citrix.com>

On 05.08.2022 12:38, Andrew Cooper wrote:
> There is a corner case where a VT-x guest which manages to reliably trigger
> non-fatal #MC's could evade the rogue RSB speculation protections that were
> supposed to be in place.
> 
> This is a lack of defence in depth; Xen does not architecturally execute more
> RET than CALL instructions, so an attacker would have to locate a different
> gadget (e.g. SpectreRSB) first to execute a transient path of excess RET
> instructions.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>

Reviewed-by: Jan Beulich <jbeulich@suse.com>



  reply	other threads:[~2022-08-05 10:50 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-05 10:38 [PATCH] x86/spec-ctrl: Use IST RSB protection for !SVM systems Andrew Cooper
2022-08-05 10:49 ` Jan Beulich [this message]
2022-08-15  8:26 ` Jan Beulich
2022-08-15  9:33   ` Andrew Cooper
2022-08-15  9:41     ` Jan Beulich

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