From: Paolo Bonzini pbonzini@redhat.com
[ Upstream commit 51776043afa415435c7e4636204fbe4f7edc4501 ]
This ioctl is obsolete (it was used by Xenner as far as I know) but still let's not break it gratuitously... Its handler is copying directly into struct kvm. Go through a bounce buffer instead, with the added benefit that we can actually do something useful with the flags argument---the previous code was exiting with -EINVAL but still doing the copy.
This technically is a userspace ABI breakage, but since no one should be using the ioctl, it's a good occasion to see if someone actually complains.
Cc: kernel-hardening@lists.openwall.com Cc: Kees Cook keescook@chromium.org Cc: Radim Krčmář rkrcmar@redhat.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Kees Cook keescook@chromium.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- arch/x86/kvm/x86.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 3aaaf305420d..803bb452aac6 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4130,13 +4130,14 @@ long kvm_arch_vm_ioctl(struct file *filp, mutex_unlock(&kvm->lock); break; case KVM_XEN_HVM_CONFIG: { + struct kvm_xen_hvm_config xhc; r = -EFAULT; - if (copy_from_user(&kvm->arch.xen_hvm_config, argp, - sizeof(struct kvm_xen_hvm_config))) + if (copy_from_user(&xhc, argp, sizeof(xhc))) goto out; r = -EINVAL; - if (kvm->arch.xen_hvm_config.flags) + if (xhc.flags) goto out; + memcpy(&kvm->arch.xen_hvm_config, &xhc, sizeof(xhc)); r = 0; break; }