Re: [PATCH 3.4 081/177] KVM: x86: Emulator fixes for eip canonical checks on near branches

[Zefan Li]

On 2015/1/28 16:49, Nadav Amit wrote:
> There is a bug in this patch, so please include
> 7e46dddd6f6cd5dbf3c7bd04a7e75d19475ac9f2 ("KVM: x86: Fix far-jump to
> non-canonical checkâ) as well.

Applied. Thanks!

> 
> Regards,
> Nadav
> 
> lizf@xxxxxxxxxx wrote:
> 
>> From: Nadav Amit <namit@xxxxxxxxxxxxxxxxx>
>>
>> 3.4.106-rc1 review patch.  If anyone has any objections, please let me know.
>>
>> ------------------
>>
>>
>> commit 234f3ce485d54017f15cf5e0699cff4100121601 upstream.
>>
>> Before changing rip (during jmp, call, ret, etc.) the target should be asserted
>> to be canonical one, as real CPUs do.  During sysret, both target rsp and rip
>> should be canonical. If any of these values is noncanonical, a #GP exception
>> should occur.  The exception to this rule are syscall and sysenter instructions
>> in which the assigned rip is checked during the assignment to the relevant
>> MSRs.
>>
>> This patch fixes the emulator to behave as real CPUs do for near branches.
>> Far branches are handled by the next patch.
>>
>> This fixes CVE-2014-3647.
>>
>> Signed-off-by: Nadav Amit <namit@xxxxxxxxxxxxxxxxx>
>> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
>> [lizf: Backported to 3.4:
>> - adjust context
>> - use ctxt->regs rather than reg_read() and reg_write()]
>> Signed-off-by: Zefan Li <lizefan@xxxxxxxxxx>


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