Re: [PATCH] KVM: coalesced_mmio: NULLify the pointers before freeing ring page and dev

[Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>]

Wei Yongjun wrote:
> Takuya Yoshikawa wrote:
>> kvm_coalesced_mmio_init() keeps to hold the addresses of a coalesced mmio
>> ring page and dev even after it has freed them.
>>
>> This may trigger problems, e.g., if we call kvm_coalesced_mmio_free() in
>> kvm_destroy_vm() or kvm_vm_ioctl_register_coalesced_mmio() afterward.
>>
>> This patch avoids such problems by NULLifying the pointers.
>>   
> 
> After this patch, I think we also need to do some check in
> kvm_vcpu_fault() for coalesced_mmio_ring, since the coalesced_mmio
> may not be init correctly. This is other issue, so I will send a
> new patch for this.

Eh, thanks.

> 
>> Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
>> ---
>>  virt/kvm/coalesced_mmio.c |    2 ++
>>  1 files changed, 2 insertions(+), 0 deletions(-)
>>
>> diff --git a/virt/kvm/coalesced_mmio.c b/virt/kvm/coalesced_mmio.c
>> index 5169736..11776b7 100644
>> --- a/virt/kvm/coalesced_mmio.c
>> +++ b/virt/kvm/coalesced_mmio.c
>> @@ -119,8 +119,10 @@ int kvm_coalesced_mmio_init(struct kvm *kvm)
>>  	return ret;
>>  
>>  out_free_dev:
>> +	kvm->coalesced_mmio_dev = NULL;
>>  	kfree(dev);
>>  out_free_page:
>> +	kvm->coalesced_mmio_ring = NULL;
>>  	__free_page(page);
>>  out_err:
>>  	return ret;
>>   
> --
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