| From | Oliver Upton <> | Date | Mon, 18 Apr 2022 10:14:42 -0700 | Subject | Re: [PATCH 5.17 183/219] KVM: Dont create VM debugfs files outside of the VM directory |
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Hi Greg,
On Mon, Apr 18, 2022 at 5:24 AM Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote: > > From: Oliver Upton <oupton@google.com> > > commit a44a4cc1c969afec97dbb2aedaf6f38eaa6253bb upstream. > > Unfortunately, there is no guarantee that KVM was able to instantiate a > debugfs directory for a particular VM. To that end, KVM shouldn't even > attempt to create new debugfs files in this case. If the specified > parent dentry is NULL, debugfs_create_file() will instantiate files at > the root of debugfs. > > For arm64, it is possible to create the vgic-state file outside of a > VM directory, the file is not cleaned up when a VM is destroyed. > Nonetheless, the corresponding struct kvm is freed when the VM is > destroyed. > > Nip the problem in the bud for all possible errant debugfs file > creations by initializing kvm->debugfs_dentry to -ENOENT. In so doing, > debugfs_create_file() will fail instead of creating the file in the root > directory. > > Cc: stable@kernel.org > Fixes: 929f45e32499 ("kvm: no need to check return value of debugfs_create functions") > Signed-off-by: Oliver Upton <oupton@google.com> > Signed-off-by: Marc Zyngier <maz@kernel.org> > Link: https://lore.kernel.org/r/20220406235615.1447180-2-oupton@google.com > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Can you drop this patch from stable for the time being? There's a bug in it because KVM does init/destroy awkwardly. Sean working on a fix [1].
[1]: https://lore.kernel.org/kvm/20220415004622.2207751-1-seanjc@google.com/
-- Thanks, Oliver
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