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From: Oliver Upton <oliver.upton@linux.dev>
To: Sebastian Ene <sebastianene@google.com>
Cc: catalin.marinas@arm.com, gshan@redhat.com, james.morse@arm.com,
	mark.rutland@arm.com, maz@kernel.org, rananta@google.com,
	ricarkol@google.com, ryan.roberts@arm.com, shahuang@redhat.com,
	suzuki.poulose@arm.com, will@kernel.org, yuzenghui@huawei.com,
	kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, kernel-team@android.com,
	vdonnefort@google.com
Subject: Re: [PATCH v5 3/4] KVM: arm64: Register ptdump with debugfs on guest creation
Date: Tue, 13 Feb 2024 16:51:12 +0000	[thread overview]
Message-ID: <ZcueAGbQISkxaTNR@linux.dev> (raw)
In-Reply-To: <Zcub87FwaVPkCXQE@google.com>

On Tue, Feb 13, 2024 at 04:42:27PM +0000, Sebastian Ene wrote:
> On Tue, Feb 13, 2024 at 12:56:20AM +0000, Oliver Upton wrote:
> > On Wed, Feb 07, 2024 at 02:48:32PM +0000, Sebastian Ene wrote:

[...]

> > > +static int kvm_ptdump_guest_open(struct inode *inode, struct file *file)
> > > +{
> > > +	return single_open(file, kvm_ptdump_guest_show, inode->i_private);
> > > +}
> > > +
> > 
> > Shouldn't we take a reference on the KVM struct at open to avoid UAF?
> > 
> > 	struct kvm *kvm = inode->i_private;
> > 
> > 	if (!kvm_get_kvm_safe(kvm))
> > 		return -ENOENT;
> > 
> > Then you can do a put on it at close().
> > 
> 
> Thanks, I though that the kvm_destroy_vm_debugfs will keep spinning if
> there are opened paths to the debugfs entry, but I guess nothing prevents
> that from happening and the kvm struct can be removed behind our back.

kvm_destroy_vm() will get called after the last put() on a kvm struct,
so all debugfs files should be closed too if we're consistent about
this.

-- 
Thanks,
Oliver

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  reply	other threads:[~2024-02-13 16:51 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-02-07 14:48 [PATCH v5 0/4] arm64: ptdump: View the second stage page-tables Sebastian Ene
2024-02-07 14:48 ` [PATCH v5 1/4] arm64: ptdump: Expose the attribute parsing functionality Sebastian Ene
2024-02-07 14:48 ` [PATCH v5 2/4] arm64: ptdump: Use the mask from the state structure Sebastian Ene
2024-02-07 14:48 ` [PATCH v5 3/4] KVM: arm64: Register ptdump with debugfs on guest creation Sebastian Ene
2024-02-13  0:56   ` Oliver Upton
2024-02-13 16:42     ` Sebastian Ene
2024-02-13 16:51       ` Oliver Upton [this message]
2024-02-07 14:48 ` [PATCH v5 4/4] KVM: arm64: Initialize the ptdump parser with stage-2 attributes Sebastian Ene
2024-02-13  0:42   ` Oliver Upton
2024-02-13 16:59     ` Sebastian Ene
2024-02-13 17:10       ` Oliver Upton
2024-02-14 16:29         ` Sebastian Ene

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