Re: [kvm:next 1/1] arch/x86/kvm/emulate.c:232 writeback_registers() error: buffer overflow 'ctxt->_regs' 9 <= 15

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On 11/09/12 22:31, Fengguang Wu wrote:
Hi Avi,

In the kvm/next branch, sparse warns about

arch/x86/kvm/emulate.c:232 writeback_registers() error: buffer overflow 'ctxt->_regs' 9 <= 15

This is because the array definition is ctxt._regs[NR_VCPU_REGS] where
NR_VCPU_REGS=9 for i386 and 17 for x86_64.

It could be fixed by changing the hard coded 16 to (NR_VCPU_REGS-1).

Hi Fengguang,

You replaced 16 to NR_VCPU_REGS in your patch, not (NR_VCPU_REGS-1).
I guess it's a mistake in your commitlog, right?


And I wonder whether you actually want NR_VCPU_REGS here?

Thanks,
Fengguang
---
--- linux-next.orig/arch/x86/kvm/emulate.c	2012-09-11 20:14:00.537475301 +0800
+++ linux-next/arch/x86/kvm/emulate.c	2012-09-11 22:21:57.569227558 +0800
@@ -228,7 +228,7 @@ static void writeback_registers(struct x
  {
  	unsigned reg;

-	for_each_set_bit(reg, (ulong *)&ctxt->regs_dirty, 16)
+	for_each_set_bit(reg, (ulong *)&ctxt->regs_dirty, NR_VCPU_REGS)


  		ctxt->ops->write_gpr(ctxt, reg, ctxt->_regs[reg]);
  }



--
			Amos.
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