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SubjectRe: [PATCH] kvm: Use struct_size() in kmalloc()
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Hi all,

Friendly ping:

Who can take this?

Thanks
--
Gustavo

On 1/4/19 10:29 AM, Gustavo A. R. Silva wrote:
> One of the more common cases of allocation size calculations is finding
> the size of a structure that has a zero-sized array at the end, along
> with memory for some number of elements for that array. For example:
>
> struct foo {
> int stuff;
> void *entry[];
> };
>
> instance = kmalloc(sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL);
>
> Instead of leaving these open-coded and prone to type mistakes, we can
> now use the new struct_size() helper:
>
> instance = kmalloc(struct_size(instance, entry, count), GFP_KERNEL);
>
> This code was detected with the help of Coccinelle.
>
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> ---
> virt/kvm/kvm_main.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 666d0155662d..635b12fdbab8 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -3709,8 +3709,8 @@ 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 = kmalloc(sizeof(*bus) + ((bus->dev_count + 1) *
> - sizeof(struct kvm_io_range)), GFP_KERNEL);
> + new_bus = kmalloc(struct_size(bus, range, bus->dev_count + 1),
> + GFP_KERNEL);
> if (!new_bus)
> return -ENOMEM;
>
> @@ -3755,8 +3755,8 @@ void kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx,
> if (i == bus->dev_count)
> return;
>
> - new_bus = kmalloc(sizeof(*bus) + ((bus->dev_count - 1) *
> - sizeof(struct kvm_io_range)), GFP_KERNEL);
> + new_bus = kmalloc(struct_size(bus, range, bus->dev_count - 1),
> + GFP_KERNEL);
> if (!new_bus) {
> pr_err("kvm: failed to shrink bus, removing it completely\n");
> goto broken;
>

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