Re: [PATCH] KVM: x86: SYSENTER emulation is broken

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On Tue, Mar 10, 2015 at 08:29:01PM +0800, Zhiqiang Zhang wrote:
> From: Nadav Amit <namit@xxxxxxxxxxxxxxxxx>
> 
> commit f3747379accba8e95d70cec0eae0582c8c182050 upstream
> 
> SYSENTER emulation is broken in several ways:
> 1. It misses the case of 16-bit code segments completely (CVE-2015-0239).
> 2. MSR_IA32_SYSENTER_CS is checked in 64-bit mode incorrectly (bits 0 and 1 can
>    still be set without causing #GP).
> 3. MSR_IA32_SYSENTER_EIP and MSR_IA32_SYSENTER_ESP are not masked in
>    legacy-mode.
> 4. There is some unneeded code.
> 
> Fix it.
> 
> Cc: stable@xxxxxxxxxxxxxx
> Signed-off-by: Nadav Amit <namit@xxxxxxxxxxxxxxxxx>
> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> [zhangzhiqiang: backport to 3.10:
>  - adjust context
>  - in 3.10 context "ctxt->eflags &= ~(EFLG_VM | EFLG_IF | EFLG_RF)" is replaced by
>    "ctxt->eflags &= ~(EFLG_VM | EFLG_IF)" in upstream, which was changed by another commit.
>  - After the above adjustments, becomes same to the original patch:
>        https://github.com/torvalds/linux/commit/f3747379accba8e95d70cec0eae0582c8c182050
> ]
> Signed-off-by: Zhiqiang Zhang <zhangzhiqiang.zhang@xxxxxxxxxx>
> ---
>  arch/x86/kvm/emulate.c | 27 ++++++++-------------------
>  1 file changed, 8 insertions(+), 19 deletions(-)

What about a backport to 3.14-stable as well?

thanks,

greg k-h
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