From 91702980566c39210225154c2a8b1cef41942737 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 26 Oct 2017 15:45:47 +0200 Subject: [PATCH 83/93] kvm: x86: fix KVM_XEN_HVM_CONFIG ioctl MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit [ Upstream commit 51776043afa415435c7e4636204fbe4f7edc4501 ] This ioctl is obsolete (it was used by Xenner as far as I know) but still let's not break it gratuitously...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 Cc: Radim Krčmář Signed-off-by: Paolo Bonzini Signed-off-by: Kees Cook Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- 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 27e6cf0..d7974fc 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4106,13 +4106,14 @@ 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; } -- 2.7.4