Re: [Xen-devel] [PATCH] x86/32on64: zero-extend hypercall index before use in memory access (debug mode only)

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> On 15.12.10 at 23:21, Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:
> On 12/15/2010 02:50 AM, Jan Beulich wrote:
>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
>>
>> --- 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
> 
> Is the second line part of the fix, or just a drive-by tweak?

The latter (sorry, I couldn't withstand, as I was surprised I
didn't do so when I created this code as a clone of its native
counterpart).

Jan


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