Call kvm_init() only after _all_ setup is complete, as kvm_init() exposes
/dev/kvm to userspace and thus allows userspace to create VMs (and call
other ioctls). E.g. KVM will encounter a NULL pointer when attempting to
add a vCPU to the per-CPU loaded_vmcss_on_cpu list if userspace is able to
create a VM before vmx_init() configures said list.
BUG: kernel NULL pointer dereference, address: 0000000000000008
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 0 P4D 0
Oops: 0002 [#1] SMP
CPU: 6 PID: 1143 Comm: stable Not tainted 6.0.0-rc7+ #988
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
RIP: 0010:vmx_vcpu_load_vmcs+0x68/0x230 [kvm_intel]
<TASK>
vmx_vcpu_load+0x16/0x60 [kvm_intel]
kvm_arch_vcpu_load+0x32/0x1f0 [kvm]
vcpu_load+0x2f/0x40 [kvm]
kvm_arch_vcpu_create+0x231/0x310 [kvm]
kvm_vm_ioctl+0x79f/0xe10 [kvm]
? handle_mm_fault+0xb1/0x220
__x64_sys_ioctl+0x80/0xb0
do_syscall_64+0x2b/0x50
entry_SYSCALL_64_after_hwframe+0x46/0xb0
RIP: 0033:0x7f5a6b05743b
</TASK>
Modules linked in: vhost_net vhost vhost_iotlb tap kvm_intel(+) kvm irqbypass
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/vmx/vmx.c | 34 +++++++++++++++++++++-------------
1 file changed, 21 insertions(+), 13 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 8e81cd94407d..76185a7a7ded 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -8521,19 +8521,23 @@ static void vmx_cleanup_l1d_flush(void)
l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_AUTO;
}
-static void vmx_exit(void)
+static void __vmx_exit(void)
{
+ allow_smaller_maxphyaddr = false;
+
#ifdef CONFIG_KEXEC_CORE
RCU_INIT_POINTER(crash_vmclear_loaded_vmcss, NULL);
synchronize_rcu();
#endif
-
- kvm_exit();
- kvm_x86_vendor_exit();
-
vmx_cleanup_l1d_flush();
+}
- allow_smaller_maxphyaddr = false;
+static void vmx_exit(void)
+{
+ kvm_exit();
+ kvm_x86_vendor_exit();
+
+ __vmx_exit();
}
module_exit(vmx_exit);
@@ -8551,11 +8555,6 @@ static int __init vmx_init(void)
if (r)
return r;
- r = kvm_init(&vmx_init_ops, sizeof(struct vcpu_vmx),
- __alignof__(struct vcpu_vmx), THIS_MODULE);
- if (r)
- goto err_kvm_init;
-
/*
* Must be called after common x86 init so enable_ept is properly set
* up. Hand the parameter mitigation value in which was stored in
@@ -8589,11 +8588,20 @@ static int __init vmx_init(void)
if (!enable_ept)
allow_smaller_maxphyaddr = true;
+ /*
+ * Common KVM initialization _must_ come last, after this, /dev/kvm is
+ * exposed to userspace!
+ */
+ r = kvm_init(&vmx_init_ops, sizeof(struct vcpu_vmx),
+ __alignof__(struct vcpu_vmx), THIS_MODULE);
+ if (r)
+ goto err_kvm_init;
+
return 0;
-err_l1d_flush:
- vmx_exit();
err_kvm_init:
+ __vmx_exit();
+err_l1d_flush:
kvm_x86_vendor_exit();
return r;
}
--
2.38.1.584.g0f3c55d4c2-goog
