linux-kernel - RE: [PATCH v4] vfio: fix potential deadlock on vfio group lock

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <BN9PR11MB52761554526A0278B13CB2B18CC69@BN9PR11MB5276.namprd11.prod.outlook.com>
Date:   Tue, 17 Jan 2023 09:05:40 +0000
From:   "Tian, Kevin" <kevin.tian@...el.com>
To:     Matthew Rosato <mjrosato@...ux.ibm.com>,
        "alex.williamson@...hat.com" <alex.williamson@...hat.com>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>
CC:     "jgg@...dia.com" <jgg@...dia.com>,
        "cohuck@...hat.com" <cohuck@...hat.com>,
        "farman@...ux.ibm.com" <farman@...ux.ibm.com>,
        "pmorel@...ux.ibm.com" <pmorel@...ux.ibm.com>,
        "borntraeger@...ux.ibm.com" <borntraeger@...ux.ibm.com>,
        "frankja@...ux.ibm.com" <frankja@...ux.ibm.com>,
        "imbrenda@...ux.ibm.com" <imbrenda@...ux.ibm.com>,
        "david@...hat.com" <david@...hat.com>,
        "akrowiak@...ux.ibm.com" <akrowiak@...ux.ibm.com>,
        "jjherne@...ux.ibm.com" <jjherne@...ux.ibm.com>,
        "pasic@...ux.ibm.com" <pasic@...ux.ibm.com>,
        "zhenyuw@...ux.intel.com" <zhenyuw@...ux.intel.com>,
        "Wang, Zhi A" <zhi.a.wang@...el.com>,
        "Christopherson,, Sean" <seanjc@...gle.com>,
        "linux-s390@...r.kernel.org" <linux-s390@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "intel-gvt-dev@...ts.freedesktop.org" 
        <intel-gvt-dev@...ts.freedesktop.org>,
        "intel-gfx@...ts.freedesktop.org" <intel-gfx@...ts.freedesktop.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v4] vfio: fix potential deadlock on vfio group lock

> From: Matthew Rosato <mjrosato@...ux.ibm.com>
> Sent: Saturday, January 14, 2023 8:04 AM
>
>  void vfio_device_group_close(struct vfio_device *device)
>  {
> +	void (*put_kvm)(struct kvm *kvm);
> +	struct kvm *kvm;
> +
>  	mutex_lock(&device->group->group_lock);
> +	kvm = device->kvm;
> +	put_kvm = device->put_kvm;
>  	vfio_device_close(device, device->group->iommufd);
> +	if (kvm == device->kvm)
> +		kvm = NULL;

Add a simple comment that this check is to detect the last close

> +void vfio_kvm_put_kvm(void (*put)(struct kvm *kvm), struct kvm *kvm)
> +{
> +	if (WARN_ON(!put))
> +		return;

also WARN_ON(!kvm)?

otherwise this looks good to me:

Reviewed-by: Kevin Tian <kevin.tian@...el.com>