[PATCH] Purify x86_decode_insn() error case management

[PATCH] Purify x86_decode_insn() error case management

[Laurent Vivier]

Purify x86_decode_insn() error case management,
the only valid case is on protected page access, other cases are errors

Signed-off-by: Laurent Vivier <Laurent.Vivier-6ktuUTfB/bM@public.gmane.org>
---
 drivers/kvm/kvm_main.c |   10 +++++++---
 1 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index cecdb1b..60798e3 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -1272,7 +1272,7 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
 			u16 error_code,
 			int no_decode)
 {
-	int r = 0;
+	int r;
 
 	vcpu->mmio_fault_cr2 = cr2;
 	kvm_x86_ops->cache_regs(vcpu);
@@ -1315,10 +1315,14 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
 					get_segment_base(vcpu, VCPU_SREG_FS);
 
 		r = x86_decode_insn(&vcpu->emulate_ctxt, &emulate_ops);
+		if (r)  {
+			if (kvm_mmu_unprotect_page_virt(vcpu, cr2))
+				return EMULATE_DONE;
+			return EMULATE_FAIL;
+		}
 	}
 
-	if (r == 0)
-		r = x86_emulate_insn(&vcpu->emulate_ctxt, &emulate_ops);
+	r = x86_emulate_insn(&vcpu->emulate_ctxt, &emulate_ops);
 
 	if (vcpu->pio.string)
 		return EMULATE_DO_MMIO;
-- 
1.5.2.4


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Re: [PATCH] Purify x86_decode_insn() error case management

[Avi Kivity]

Laurent Vivier wrote:
> Purify x86_decode_insn() error case management,
> the only valid case is on protected page access, other cases are errors
>
>   

Applied, thanks.


-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.


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Defy all challenges. Microsoft(R) Visual Studio 2005.
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