From 93fd9666c269877fffb74e14f52792d9c000c1f2 Mon Sep 17 00:00:00 2001 From: Suravee Suthikulpanit Date: Fri, 21 Feb 2020 08:52:17 -0600 Subject: [PATCH] kvm: x86: svm: Fix NULL pointer dereference when AVIC not enabled Launching VM w/ AVIC disabled together with pass-through device results in NULL pointer dereference bug with the following call trace. RIP: 0010:svm_refresh_apicv_exec_ctrl+0x17e/0x1a0 [kvm_amd] Call Trace: kvm_vcpu_update_apicv+0x44/0x60 [kvm] kvm_arch_vcpu_ioctl_run+0x3f4/0x1c80 [kvm] kvm_vcpu_ioctl+0x3d8/0x650 [kvm] do_vfs_ioctl+0xaa/0x660 ? tomoyo_file_ioctl+0x19/0x20 ksys_ioctl+0x67/0x90 __x64_sys_ioctl+0x1a/0x20 do_syscall_64+0x57/0x190 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Investigation shows that this is due to the uninitialized usage of struct vapu_svm.ir_list in the svm_set_pi_irte_mode(), which is called from svm_refresh_apicv_exec_ctrl(). The ir_list is initialized only if AVIC is enabled. So, fixes by adding a check if AVIC is enabled in the svm_refresh_apicv_exec_ctrl(). Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=206579 Fixes: 8937d762396d ("kvm: x86: svm: Add support to (de)activate posted interrupts.") Signed-off-by: Suravee Suthikulpanit Tested-by: Alex Williamson Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index bef0ba35f121..a391b29138f0 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -5232,6 +5232,9 @@ static void svm_refresh_apicv_exec_ctrl(struct kvm_vcpu *vcpu) struct vmcb *vmcb = svm->vmcb; bool activated = kvm_vcpu_apicv_active(vcpu); + if (!avic) + return; + if (activated) { /** * During AVIC temporary deactivation, guest could update -- 2.11.0