linux-kernel - Re: [PATCH] KVM: Fix OOM vulnerability caused by continuously creating devices

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Message-ID: <Ydxa2ndP/Qrggo90@google.com>
Date:   Mon, 10 Jan 2022 16:12:10 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Yi Wang <wang.yi59@....com.cn>
Cc:     pbonzini@...hat.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, xue.zhihong@....com.cn,
        wang.liang82@....com.cn, ZhaoQiang <zhao.qiang11@....com.cn>
Subject: Re: [PATCH] KVM: Fix OOM vulnerability caused by continuously
 creating devices

On Sun, Jan 09, 2022, Yi Wang wrote:
> From: ZhaoQiang <zhao.qiang11@....com.cn>
> 
> When processing the ioctl request for creating a device in the
> kvm_vm_ioctl()function,the branch did not reclaim the successfully
> created device,which caused memory leak.

It's not a memory leak, kvm_destroy_vm() => kvm_destroy_devices() will free all
devices. anon_inode_getfd() installes the devices fd, so the device's fd and its
reference to KVM will be put when the process exits.  Am I missing something?