x86/32on64: zero-extend hypercall index before use in memory access (debug mode only)

Signed-off-by: Jan Beulich <jbeulich@novell.com>

diff --git a/xen/arch/x86/x86_64/compat/entry.S b/xen/arch/x86/x86_64/compat/entry.S
index d668822cbb4676bb9e8a00106e537dfcd06db183..1da17b2cab1033d7451e96596322d801a1fe2fcf 100644 (file)
--- a/xen/arch/x86/x86_64/compat/entry.S
+++ b/xen/arch/x86/x86_64/compat/entry.S
@@ -25,7 +25,8 @@ ENTRY(compat_hypercall)
         pushq UREGS_rbx(%rsp); pushq %rcx; pushq %rdx; pushq %rsi; pushq %rdi
         pushq UREGS_rbp+5*8(%rsp)
         leaq  compat_hypercall_args_table(%rip),%r10
-        movq  $6,%rcx
+        movl  %eax,%eax
+        movl  $6,%ecx
         subb  (%r10,%rax,1),%cl
         movq  %rsp,%rdi
         movl  $0xDEADBEEF,%eax