[Qemu-devel] [RESEND PATCH] Fix qemu crash with kvm enabled.

[Qemu-devel] [RESEND PATCH] Fix qemu crash with kvm enabled.

[Gerd Hoffmann]

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  Hi,

If you see crashes after commit 6060, try this one ;)

Not initializing msr_list.nmsrs before the KVM_GET_MSR_INDEX_LIST ioctl
will make the kernel fill too much data into msr_list, thereby
overflowing the stack and crashing the qemu.

cheers,
  Gerd

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>From cb6c5b6fde117fe05699230c43c3163e91dbb3cd Mon Sep 17 00:00:00 2001
From: Gerd Hoffmann <kraxel@redhat.com>
Date: Tue, 9 Dec 2008 17:42:27 +0100
Subject: [PATCH] Fix qemu crash with kvm enabled.


Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 target-i386/kvm.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index effd5af..db11ac2 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -104,11 +104,11 @@ static int kvm_has_msr_star(CPUState *env)
 
         /* Obtain MSR list from KVM.  These are the MSRs that we must
          * save/restore */
+        msr_list.nmsrs = 0;
         ret = kvm_ioctl(env->kvm_state, KVM_GET_MSR_INDEX_LIST, &msr_list);
         if (ret < 0)
             return 0;
 
-        msr_list.nmsrs = 0;
         kvm_msr_list = qemu_mallocz(sizeof(msr_list) +
                                     msr_list.nmsrs * sizeof(msr_list.indices[0]));
         if (kvm_msr_list == NULL)
-- 
1.5.6.5

Re: [Qemu-devel] [RESEND PATCH] Fix qemu crash with kvm enabled.

[Anthony Liguori]

Gerd Hoffmann wrote:
>   Hi,
>
> If you see crashes after commit 6060, try this one ;)
>
> Not initializing msr_list.nmsrs before the KVM_GET_MSR_INDEX_LIST ioctl
> will make the kernel fill too much data into msr_list, thereby
> overflowing the stack and crashing the qemu.
>   

I've applied that.  Or at least I thoguht I did.

Regards,

Anthony Liguori

> cheers,
>   Gerd
>   

Re: [Qemu-devel] [RESEND PATCH] Fix qemu crash with kvm enabled.

[Gerd Hoffmann]

Anthony Liguori wrote:
> Gerd Hoffmann wrote:
>>   Hi,
>>
>> If you see crashes after commit 6060, try this one ;)
>>
>> Not initializing msr_list.nmsrs before the KVM_GET_MSR_INDEX_LIST ioctl
>> will make the kernel fill too much data into msr_list, thereby
>> overflowing the stack and crashing the qemu.
> 
> I've applied that.  Or at least I thoguht I did.

Yes, is in, I somehow missed the commit message.

thanks,
  Gerd