Re: [PATCH V2 1/3] kvm: use kmalloc() instead of kzalloc() during iodev register/unregister

[Joe Perches <joe@perches.com>]

On Tue, 2015-08-25 at 15:47 +0800, Jason Wang wrote:
> All fields of kvm_io_range were initialized or copied explicitly
> afterwards. So switch to use kmalloc().

Is there any compiler added alignment padding
in either structure?  If so, those padding
areas would now be uninitialized and may leak
kernel data if copied to user-space.

> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
[]
> @@ -3248,7 +3248,7 @@ int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
>  	if (bus->dev_count - bus->ioeventfd_count > NR_IOBUS_DEVS - 1)
>  		return -ENOSPC;
>  
> -	new_bus = kzalloc(sizeof(*bus) + ((bus->dev_count + 1) *
> +	new_bus = kmalloc(sizeof(*bus) + ((bus->dev_count + 1) *
>  			  sizeof(struct kvm_io_range)), GFP_KERNEL);
>  	if (!new_bus)
>  		return -ENOMEM;
> @@ -3280,7 +3280,7 @@ int kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx,
>  	if (r)
>  		return r;
>  
> -	new_bus = kzalloc(sizeof(*bus) + ((bus->dev_count - 1) *
> +	new_bus = kmalloc(sizeof(*bus) + ((bus->dev_count - 1) *
>  			  sizeof(struct kvm_io_range)), GFP_KERNEL);
>  	if (!new_bus)
>  		return -ENOMEM;