From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Eugene Korenevsky <ekorenevsky@gmail.com>,
kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH v4 1/2] kvm: vmx: fix limit checking in get_vmx_mem_address()
Date: Thu, 6 Jun 2019 11:18:36 -0700 [thread overview]
Message-ID: <20190606181835.GH23169@linux.intel.com> (raw)
In-Reply-To: <20190605211739.GA21798@dnote>
On Thu, Jun 06, 2019 at 12:17:39AM +0300, Eugene Korenevsky wrote:
> Intel SDM vol. 3, 5.3:
> The processor causes a
> general-protection exception (or, if the segment is SS, a stack-fault
> exception) any time an attempt is made to access the following addresses
> in a segment:
> - A byte at an offset greater than the effective limit
> - A word at an offset greater than the (effective-limit – 1)
> - A doubleword at an offset greater than the (effective-limit – 3)
> - A quadword at an offset greater than the (effective-limit – 7)
>
> Therefore, the generic limit checking error condition must be
>
> exn = (off > limit + 1 - access_len) = (off + access_len - 1 > limit)
>
> but not
>
> exn = (off + access_len > limit)
>
> as for now.
>
> Also avoid integer overflow of `off` at 32-bit KVM by casting it to u64.
>
> Note: access length is currently sizeof(u64) which is incorrect. This
> will be fixed in the subsequent patch.
>
> Signed-off-by: Eugene Korenevsky <ekorenevsky@gmail.com>
> ---
Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
prev parent reply other threads:[~2019-06-06 18:18 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-05 21:17 [PATCH v4 1/2] kvm: vmx: fix limit checking in get_vmx_mem_address() Eugene Korenevsky
2019-06-06 18:18 ` Sean Christopherson [this message]
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