From: Kees Cook <keescook@chromium.org>
To: Sean Christopherson <seanjc@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Robert Dinse <nanook@eskimo.com>
Subject: Re: [PATCH v2 7/8] KVM: x86: Bug the VM if the emulator generates a bogus exception vector
Date: Tue, 31 May 2022 11:06:12 -0700 [thread overview]
Message-ID: <202205311106.58FC5B61@keescook> (raw)
In-Reply-To: <20220526210817.3428868-8-seanjc@google.com>
On Thu, May 26, 2022 at 09:08:16PM +0000, Sean Christopherson wrote:
> Bug the VM if KVM's emulator attempts to inject a bogus exception vector.
> The guest is likely doomed even if KVM continues on, and propagating a
> bad vector to the rest of KVM runs the risk of breaking other assumptions
> in KVM and thus triggering a more egregious bug.
>
> All existing users of emulate_exception() have hardcoded vector numbers
> (__load_segment_descriptor() uses a few different vectors, but they're
> all hardcoded), and future users are likely to follow suit, i.e. the
> change to emulate_exception() is a glorified nop.
>
> As for the ctxt->exception.vector check in x86_emulate_insn(), the few
> known times the WARN has been triggered in the past is when the field was
> not set when synthesizing a fault, i.e. for all intents and purposes the
> check protects against consumption of uninitialized data.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
--
Kees Cook
next prev parent reply other threads:[~2022-05-31 18:06 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-26 21:08 [PATCH v2 0/8] KVM: x86: Emulator _regs fixes and cleanups Sean Christopherson
2022-05-26 21:08 ` [PATCH v2 1/8] KVM: x86: Grab regs_dirty in local 'unsigned long' Sean Christopherson
2022-05-26 21:08 ` [PATCH v2 2/8] KVM: x86: Harden _regs accesses to guard against buggy input Sean Christopherson
2022-05-26 21:08 ` [PATCH v2 3/8] KVM: x86: Omit VCPU_REGS_RIP from emulator's _regs array Sean Christopherson
2022-05-31 18:04 ` Kees Cook
2022-05-26 21:08 ` [PATCH v2 4/8] KVM: x86: Use 16-bit fields to track dirty/valid emulator GPRs Sean Christopherson
2022-05-26 21:08 ` [PATCH v2 5/8] KVM: x86: Reduce the number of emulator GPRs to '8' for 32-bit KVM Sean Christopherson
2022-05-31 18:04 ` Kees Cook
2022-05-26 21:08 ` [PATCH v2 6/8] KVM: x86: Bug the VM if the emulator accesses a non-existent GPR Sean Christopherson
2022-05-31 18:06 ` Kees Cook
2022-06-01 8:29 ` Vitaly Kuznetsov
2022-06-02 16:01 ` Sean Christopherson
2022-05-26 21:08 ` [PATCH v2 7/8] KVM: x86: Bug the VM if the emulator generates a bogus exception vector Sean Christopherson
2022-05-31 18:06 ` Kees Cook [this message]
2022-06-01 8:31 ` Vitaly Kuznetsov
2022-05-26 21:08 ` [PATCH v2 8/8] KVM: x86: Bug the VM on an out-of-bounds data read Sean Christopherson
2022-05-31 18:06 ` Kees Cook
2022-06-01 8:39 ` Vitaly Kuznetsov
2022-05-26 23:14 ` [PATCH v2 0/8] KVM: x86: Emulator _regs fixes and cleanups Robert Dinse
2022-06-08 12:23 ` Paolo Bonzini
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