[Xen-devel] [PATCH 2/2] x86/emul: Avoid #UD when emulating v{, u}comis{s, d}

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

v{,u}comis{s,d} have two operands, so require vex.reg set to ~0.

Spotted by AFL
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
---
 xen/arch/x86/x86_emulate/x86_emulate.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c 
b/xen/arch/x86/x86_emulate/x86_emulate.c
index e09975c..08bd818 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -5673,6 +5673,7 @@ x86_emulate(
         }
         else
         {
+            generate_exception_if(vex.reg != 0xf, EXC_UD);
             host_and_vcpu_must_have(avx);
             get_fpu(X86EMUL_FPU_ymm, &fic);
         }
-- 
2.1.4


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