From: Marc Zyngier <marc.zyngier@arm.com>
To: "Alex Bennée" <alex.bennee@linaro.org>,
"Christoffer Dall" <christoffer.dall@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
Peter Maydell <peter.maydell@linaro.org>
Subject: Re: [PATCH] arm64: KVM: Fix user access for debug registers
Date: Wed, 16 Sep 2015 15:46:17 +0100 [thread overview]
Message-ID: <55F980B9.6080601@arm.com> (raw)
In-Reply-To: <87wpvqmnxw.fsf@linaro.org>
On 16/09/15 15:35, Alex Bennée wrote:
>
> Christoffer Dall <christoffer.dall@linaro.org> writes:
>
>> On Wed, Sep 16, 2015 at 11:41:10AM +0100, Marc Zyngier wrote:
>>> When setting the debug register from userspace, make sure that
>>> copy_from_user() is called with its parameters in the expected
>>> order. It otherwise doesn't do what you think.
>>>
>>> Reported-by: Peter Maydell <peter.maydell@linaro.org>
>>> Cc: Alex Bennée <alex.bennee@linaro.org>
>>> Fixes: 84e690bfbed1 ("KVM: arm64: introduce vcpu->arch.debug_ptr")
>>> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
>>
>> yikes!
>
> OK I'm now muchly confused as to how it could have worked...
Well, we only write the registers at boot time, and corrupting userspace
did go unnoticed. I was only able to reproduce this on a model with PAN
enabled.
Copy-paste bug.
M.
--
Jazz is not dead. It just smells funny...
next prev parent reply other threads:[~2015-09-16 14:46 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-16 10:41 [PATCH] arm64: KVM: Fix user access for debug registers Marc Zyngier
2015-09-16 13:41 ` Christoffer Dall
2015-09-16 14:06 ` Marc Zyngier
2015-09-16 14:35 ` Alex Bennée
2015-09-16 14:46 ` Marc Zyngier [this message]
2015-09-16 14:42 ` Alex Bennée
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