linux-kernel - Re: [PATCH] fix memory leak on kvm_vm_ioctl_create_spapr

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Message-ID: <8fd9a878-a8ce-5576-9a5c-1c221ff6ded7@redhat.com>
Date:   Tue, 22 Aug 2017 17:23:36 +0200
From:   David Hildenbrand <david@...hat.com>
To:     nixiaoming <nixiaoming@...wei.com>, agraf@...e.com,
        pbonzini@...hat.com, rkrcmar@...hat.com, benh@...nel.crashing.org,
        paulus@...ba.org, mpe@...erman.id.au
Cc:     kvm-ppc@...r.kernel.org, kvm@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] fix memory leak on kvm_vm_ioctl_create_spapr_tce

On 22.08.2017 17:15, David Hildenbrand wrote:
> On 22.08.2017 16:28, nixiaoming wrote:
>> miss kfree(stt) when anon_inode_getfd return fail
>> so add check anon_inode_getfd return val, and kfree stt
>>
>> Signed-off-by: nixiaoming <nixiaoming@...wei.com>
>> ---
>>  arch/powerpc/kvm/book3s_64_vio.c | 5 ++++-
>>  1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/kvm/book3s_64_vio.c b/arch/powerpc/kvm/book3s_64_vio.c
>> index a160c14..a0b4459 100644
>> --- a/arch/powerpc/kvm/book3s_64_vio.c
>> +++ b/arch/powerpc/kvm/book3s_64_vio.c
>> @@ -341,8 +341,11 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm,
>>  
>>  	mutex_unlock(&kvm->lock);
>>  
>> -	return anon_inode_getfd("kvm-spapr-tce", &kvm_spapr_tce_fops,
>> +	ret = anon_inode_getfd("kvm-spapr-tce", &kvm_spapr_tce_fops,
>>  				stt, O_RDWR | O_CLOEXEC);
>> +	if (ret < 0)
>> +		goto fail;
>> +	return ret;
>>  
>>  fail:
>>  	if (stt) {
>>
> 
> 
> stt has already been added to kvm->arch.spapr_tce_tables, so freeing it
> is evil IMHO. I don't know that code, so I don't know if there is some
> other place that will make sure that everything in
> kvm->arch.spapr_tce_tables will properly get freed, even when no release
> function has been called (kvm_spapr_tce_release).
> 

If it is really not freed, than also kvm_put_kvm(stt->kvm) is missing.

-- 

Thanks,

David