4.19-stable review patch. If anyone has any objections, please let me know.
------------------
From: Wanpeng Li kernellwp@gmail.com
commit 38ab012f109caf10f471db1adf284e620dd8d701 upstream.
Reported by syzkaller:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000014 PGD 800000040410c067 P4D 800000040410c067 PUD 40410d067 PMD 0 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 3 PID: 2567 Comm: poc Tainted: G OE 4.19.0-rc5 #16 RIP: 0010:kvm_pv_send_ipi+0x94/0x350 [kvm] Call Trace: kvm_emulate_hypercall+0x3cc/0x700 [kvm] handle_vmcall+0xe/0x10 [kvm_intel] vmx_handle_exit+0xc1/0x11b0 [kvm_intel] vcpu_enter_guest+0x9fb/0x1910 [kvm] kvm_arch_vcpu_ioctl_run+0x35c/0x610 [kvm] kvm_vcpu_ioctl+0x3e9/0x6d0 [kvm] do_vfs_ioctl+0xa5/0x690 ksys_ioctl+0x6d/0x80 __x64_sys_ioctl+0x1a/0x20 do_syscall_64+0x83/0x6e0 entry_SYSCALL_64_after_hwframe+0x49/0xbe
The reason is that the apic map has not yet been initialized, the testcase triggers pv_send_ipi interface by vmcall which results in kvm->arch.apic_map is dereferenced. This patch fixes it by checking whether or not apic map is NULL and bailing out immediately if that is the case.
Fixes: 4180bf1b65 (KVM: X86: Implement "send IPI" hypercall) Reported-by: Wei Wu ww9210@gmail.com Cc: Paolo Bonzini pbonzini@redhat.com Cc: Radim Krčmář rkrcmar@redhat.com Cc: Wei Wu ww9210@gmail.com Signed-off-by: Wanpeng Li wanpengli@tencent.com Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/kvm/lapic.c | 5 +++++ 1 file changed, 5 insertions(+)
--- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -571,6 +571,11 @@ int kvm_pv_send_ipi(struct kvm *kvm, uns rcu_read_lock(); map = rcu_dereference(kvm->arch.apic_map);
+ if (unlikely(!map)) { + count = -EOPNOTSUPP; + goto out; + } + if (min > map->max_apic_id) goto out; /* Bits above cluster_size are masked in the caller. */