diff options
| author | Wanpeng Li <kernellwp@gmail.com> | 2018-11-20 09:39:30 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-12-05 19:32:05 +0100 |
| commit | ffb01e73737b4d3e66734c901ee666ae8a23a857 (patch) | |
| tree | 0683d2747dce4cf19caa6563def59ae0f45005a7 /arch | |
| parent | 6d772df4038e9eb45043a062381130870a439e0c (diff) | |
KVM: LAPIC: Fix pv ipis use-before-initialization
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>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kvm/lapic.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index fbb0e6df121b..2216d21e955d 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -571,6 +571,11 @@ int kvm_pv_send_ipi(struct kvm *kvm, unsigned long ipi_bitmap_low, 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. */ |