* [PATCH] KVM: Add the check and free to avoid unknown errors.
@ 2020-02-14 21:02 Haiwei Li
2020-02-17 17:15 ` Paolo Bonzini
0 siblings, 1 reply; 4+ messages in thread
From: Haiwei Li @ 2020-02-14 21:02 UTC (permalink / raw)
To: kvm, linux-kernel; +Cc: pbonzini
From: Haiwei Li <lihaiwei@tencent.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()'.
Add the check and free to avoid unknown errors.
Signed-off-by: Haiwei Li <lihaiwei@tencent.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
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] KVM: Add the check and free to avoid unknown errors.
2020-02-14 21:02 [PATCH] KVM: Add the check and free to avoid unknown errors Haiwei Li
@ 2020-02-17 17:15 ` Paolo Bonzini
0 siblings, 0 replies; 4+ messages in thread
From: Paolo Bonzini @ 2020-02-17 17:15 UTC (permalink / raw)
To: Haiwei Li, kvm, linux-kernel
On 14/02/20 22:02, Haiwei Li wrote:
> From: Haiwei Li <lihaiwei@tencent.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@tencent.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
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] KVM: Add the check and free to avoid unknown errors.
2020-02-15 2:00 linmiaohe
@ 2020-02-15 5:33 ` Haiwei Li
0 siblings, 0 replies; 4+ messages in thread
From: Haiwei Li @ 2020-02-15 5:33 UTC (permalink / raw)
To: linmiaohe; +Cc: pbonzini, kvm, linux-kernel
linmiaohe <linmiaohe@huawei.com> 于2020年2月15日周六 上午10:00写道:
>
> Hi:
> Haiwei Li <lihaiwei.kernel@gmail.com> wrote:
> > From: Haiwei Li <lihaiwei@tencent.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()'.
> >
> > Add the check and free to avoid unknown errors.
>
> Add the check and free? According to the code,it seem what you mean is "add the check against free" ?
Right, i can change the description.
>
> >
> > Signed-off-by: Haiwei Li <lihaiwei@tencent.com>
> >
> > 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);
> > }
> > }
>
> If (!kvm->debugfs_stat_data[i]) is checked in kfree() internal. And break early seems have no different effect.
> Could you please explain what unknown errors may occur? And how? Thanks.
I get the free() code. It is just like what you said. Thanks a lot.
Break early is useful. If kvm->debugfs_stat_data[i] is null, breaking
early can reduce the check.
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] KVM: Add the check and free to avoid unknown errors.
@ 2020-02-15 2:00 linmiaohe
2020-02-15 5:33 ` Haiwei Li
0 siblings, 1 reply; 4+ messages in thread
From: linmiaohe @ 2020-02-15 2:00 UTC (permalink / raw)
To: Haiwei Li; +Cc: pbonzini, kvm, linux-kernel
Hi:
Haiwei Li <lihaiwei.kernel@gmail.com> wrote:
> From: Haiwei Li <lihaiwei@tencent.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()'.
>
> Add the check and free to avoid unknown errors.
Add the check and free? According to the code,it seem what you mean is "add the check against free" ?
>
> Signed-off-by: Haiwei Li <lihaiwei@tencent.com>
>
> 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);
> }
> }
If (!kvm->debugfs_stat_data[i]) is checked in kfree() internal. And break early seems have no different effect.
Could you please explain what unknown errors may occur? And how? Thanks.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2020-02-17 17:15 UTC | newest]
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2020-02-14 21:02 [PATCH] KVM: Add the check and free to avoid unknown errors Haiwei Li
2020-02-17 17:15 ` Paolo Bonzini
2020-02-15 2:00 linmiaohe
2020-02-15 5:33 ` Haiwei Li
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