On Sat, Nov 02, 2013 at 06:07:59PM +0800, kbuild test robot wrote:
> tree: git://git.kernel.org/pub/scm/virt/kvm/kvm.git queue
> head: 81e87e26796782e014fd1f2bb9cd8fb6ce4021a8
> commit: 9c15bb1d0a8411f9bb3395d21d5309bde7da0c1c [6/21] kvm: Add KVM_GET_EMULATED_CPUID
> reproduce: make C=1 CF=-D__CHECK_ENDIAN__
>
>
> sparse warnings: (new ones prefixed by >>)
>
> >> arch/x86/kvm/cpuid.c:564:39: sparse: dereference of noderef expression
> >> arch/x86/kvm/cpuid.c:565:39: sparse: dereference of noderef expression
> >> arch/x86/kvm/cpuid.c:566:39: sparse: dereference of noderef expression
>
> vim +564 arch/x86/kvm/cpuid.c
>
> 558 *
> 559 * Sadly, this wasn't enforced for KVM_GET_SUPPORTED_CPUID and so we
> 560 * have to give ourselves satisfied only with the emulated side. /me
> 561 * sheds a tear.
> 562 */
> 563 for (i = 0; i < num_entries; i++) {
> > 564 if (entries[i].padding[0] ||
> 565 entries[i].padding[1] ||
> 566 entries[i].padding[2])
> 567 return true;
> 568 }
> 569 return false;
Ok, how's that:
--
From: Borislav Petkov <bp@xxxxxxx>
Subject: [PATCH] kvm, cpuid: Fix sparse warning
We need to copy padding to kernel space first before looking at it.
Reported-by: kbuild test robot <fengguang.wu@xxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
---
arch/x86/kvm/cpuid.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 8f66fba804e4..c6976257eff5 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -564,6 +564,7 @@ static bool sanity_check_entries(struct kvm_cpuid_entry2 __user *entries,
__u32 num_entries, unsigned int ioctl_type)
{
int i;
+ __u32 pad[3];
if (ioctl_type != KVM_GET_EMULATED_CPUID)
return false;
@@ -577,9 +578,10 @@ static bool sanity_check_entries(struct kvm_cpuid_entry2 __user *entries,
* sheds a tear.
*/
for (i = 0; i < num_entries; i++) {
- if (entries[i].padding[0] ||
- entries[i].padding[1] ||
- entries[i].padding[2])
+ if (copy_from_user(pad, entries[i].padding, sizeof(pad)))
+ return true;
+
+ if (pad[0] || pad[1] || pad[2])
return true;
}
return false;
--
1.8.0
--
Regards/Gruss,
Boris.
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