Re: [PATCH] KVM: Use vmemdup_user()

From: Paolo Bonzini
Date: Thu Jun 04 2020 - 14:41:26 EST


On 03/06/20 12:11, Denis Efremov wrote:
> Replace opencoded alloc and copy with vmemdup_user().
>
> Signed-off-by: Denis Efremov <efremov@xxxxxxxxx>
> ---
> Looks like these are the only places in KVM that are suitable for
> vmemdup_user().
>
> arch/x86/kvm/cpuid.c | 17 +++++++----------
> virt/kvm/kvm_main.c | 19 ++++++++-----------
> 2 files changed, 15 insertions(+), 21 deletions(-)
>
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 901cd1fdecd9..27438a2bdb62 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -182,17 +182,14 @@ int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu,
> r = -E2BIG;
> if (cpuid->nent > KVM_MAX_CPUID_ENTRIES)
> goto out;
> - r = -ENOMEM;
> if (cpuid->nent) {
> - cpuid_entries =
> - vmalloc(array_size(sizeof(struct kvm_cpuid_entry),
> - cpuid->nent));
> - if (!cpuid_entries)
> - goto out;
> - r = -EFAULT;
> - if (copy_from_user(cpuid_entries, entries,
> - cpuid->nent * sizeof(struct kvm_cpuid_entry)))
> + cpuid_entries = vmemdup_user(entries,
> + array_size(sizeof(struct kvm_cpuid_entry),
> + cpuid->nent));
> + if (IS_ERR(cpuid_entries)) {
> + r = PTR_ERR(cpuid_entries);
> goto out;
> + }
> }
> for (i = 0; i < cpuid->nent; i++) {
> vcpu->arch.cpuid_entries[i].function = cpuid_entries[i].function;
> @@ -212,8 +209,8 @@ int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu,
> kvm_x86_ops.cpuid_update(vcpu);
> r = kvm_update_cpuid(vcpu);
>
> + kvfree(cpuid_entries);
> out:
> - vfree(cpuid_entries);
> return r;
> }
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 731c1e517716..46a3743e95ff 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -3722,21 +3722,18 @@ static long kvm_vm_ioctl(struct file *filp,
> if (routing.flags)
> goto out;
> if (routing.nr) {
> - r = -ENOMEM;
> - entries = vmalloc(array_size(sizeof(*entries),
> - routing.nr));
> - if (!entries)
> - goto out;
> - r = -EFAULT;
> urouting = argp;
> - if (copy_from_user(entries, urouting->entries,
> - routing.nr * sizeof(*entries)))
> - goto out_free_irq_routing;
> + entries = vmemdup_user(urouting->entries,
> + array_size(sizeof(*entries),
> + routing.nr));
> + if (IS_ERR(entries)) {
> + r = PTR_ERR(entries);
> + goto out;
> + }
> }
> r = kvm_set_irq_routing(kvm, entries, routing.nr,
> routing.flags);
> -out_free_irq_routing:
> - vfree(entries);
> + kvfree(entries);
> break;
> }
> #endif /* CONFIG_HAVE_KVM_IRQ_ROUTING */
>

Queued, thanks.

Paolo