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在 2019年9月17日，17:32，Jackie Liu liuyun01@kylinos.cn 写道：

From: Radim Krčmář rkrcmar@redhat.com

KVM was using arrays of size KVM_MAX_VCPUS with vcpu_id, but ID can be bigger that the maximal number of VCPUs, resulting in out-of-bounds access.

Found by syzkaller:

BUG: KASAN: slab-out-of-bounds in __apic_accept_irq+0xb33/0xb50 at addr [...] Write of size 1 by task a.out/27101 CPU: 1 PID: 27101 Comm: a.out Not tainted 4.9.0-rc5+ #49 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 [...] Call Trace: [...] __apic_accept_irq+0xb33/0xb50 arch/x86/kvm/lapic.c:905 [...] kvm_apic_set_irq+0x10e/0x180 arch/x86/kvm/lapic.c:495 [...] kvm_irq_delivery_to_apic+0x732/0xc10 arch/x86/kvm/irq_comm.c:86 [...] ioapic_service+0x41d/0x760 arch/x86/kvm/ioapic.c:360 [...] ioapic_set_irq+0x275/0x6c0 arch/x86/kvm/ioapic.c:222 [...] kvm_ioapic_inject_all arch/x86/kvm/ioapic.c:235 [...] kvm_set_ioapic+0x223/0x310 arch/x86/kvm/ioapic.c:670 [...] kvm_vm_ioctl_set_irqchip arch/x86/kvm/x86.c:3668 [...] kvm_arch_vm_ioctl+0x1a08/0x23c0 arch/x86/kvm/x86.c:3999 [...] kvm_vm_ioctl+0x1fa/0x1a70 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3099

Reported-by: Dmitry Vyukov dvyukov@google.com Cc: stable@vger.kernel.org Fixes: af1bae5497b9 ("KVM: x86: bump KVM_MAX_VCPU_ID to 1023") Reviewed-by: Paolo Bonzini pbonzini@redhat.com Reviewed-by: David Hildenbrand david@redhat.com Signed-off-by: Radim Krčmář rkrcmar@redhat.com Signed-off-by: Jackie Liu liuyun01@kylinos.cn

---

arch/x86/kvm/ioapic.c | 2 +- arch/x86/kvm/ioapic.h | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/ioapic.c b/arch/x86/kvm/ioapic.c index ec62df3..d25cbac 100644 --- a/arch/x86/kvm/ioapic.c +++ b/arch/x86/kvm/ioapic.c @@ -94,7 +94,7 @@ static unsigned long ioapic_read_indirect(struct kvm_ioapic *ioapic, static void rtc_irq_eoi_tracking_reset(struct kvm_ioapic *ioapic) { ioapic->rtc_status.pending_eoi = 0;

• bitmap_zero(ioapic->rtc_status.dest_map.map, KVM_MAX_VCPUS);

• bitmap_zero(ioapic->rtc_status.dest_map.map, KVM_MAX_VCPU_ID);

}

static void kvm_rtc_eoi_tracking_restore_all(struct kvm_ioapic *ioapic); diff --git a/arch/x86/kvm/ioapic.h b/arch/x86/kvm/ioapic.h index 7d2692a..1cc6e54 100644 --- a/arch/x86/kvm/ioapic.h +++ b/arch/x86/kvm/ioapic.h @@ -42,13 +42,13 @@ struct kvm_vcpu;

struct dest_map { /* vcpu bitmap where IRQ has been sent */

• DECLARE_BITMAP(map, KVM_MAX_VCPUS);

• DECLARE_BITMAP(map, KVM_MAX_VCPU_ID);

  /*

  • Vector sent to a given vcpu, only valid when
  • the vcpu's bit in map is set

  */

• u8 vectors[KVM_MAX_VCPUS];

• u8 vectors[KVM_MAX_VCPU_ID];

};

-- 2.7.4

-- BR, Jackie Liu