linux-kernel - Re: [PATCH] KVM: Add the check and free to avoid unknown errors.

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Date:   Mon, 17 Feb 2020 18:15:49 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Haiwei Li <lihaiwei.kernel@...il.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] KVM: Add the check and free to avoid unknown errors.

On 14/02/20 22:02, Haiwei Li wrote:
> From: Haiwei Li <lihaiwei@...cent.com>
> 
> If 'kvm_create_vm_debugfs()' fails in 'kzalloc(sizeof(*stat_data), ...)',
> 'kvm_destroy_vm_debugfs()' will be called by the final fput(file) in
> 'kvm_dev_ioctl_create_vm()'.

Can you explain better?  It is okay to pass NULL to kfree.

Paolo

> Add the check and free to avoid unknown errors.
> 
> Signed-off-by: Haiwei Li <lihaiwei@...cent.com>
> ---
>  virt/kvm/kvm_main.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 67ae2d5..18a32e1 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -617,8 +617,11 @@ static void kvm_destroy_vm_debugfs(struct kvm *kvm)
>      debugfs_remove_recursive(kvm->debugfs_dentry);
> 
>      if (kvm->debugfs_stat_data) {
> -        for (i = 0; i < kvm_debugfs_num_entries; i++)
> +        for (i = 0; i < kvm_debugfs_num_entries; i++) {
> +            if (!kvm->debugfs_stat_data[i])
> +                break;
>              kfree(kvm->debugfs_stat_data[i]);
> +        }
>          kfree(kvm->debugfs_stat_data);
>      }
>  }
> -- 
> 1.8.3.1
>