Commits
Radim Krčmář committed 444fdad88f3
KVM: x86: fix out-of-bounds access in lapic
Cluster xAPIC delivery incorrectly assumed that dest_id <= 0xff.
With enabled KVM_X2APIC_API_USE_32BIT_IDS in KVM_CAP_X2APIC_API, a
userspace can send an interrupt with dest_id that results in
out-of-bounds access.
Found by syzkaller:
BUG: KASAN: slab-out-of-bounds in kvm_irq_delivery_to_apic_fast+0x11fa/0x1210 at addr ffff88003d9ca750
Read of size 8 by task syz-executor/22923
CPU: 0 PID: 22923 Comm: syz-executor Not tainted 4.9.0-rc4+ #49
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
[...]
Call Trace:
[...] __dump_stack lib/dump_stack.c:15
[...] dump_stack+0xb3/0x118 lib/dump_stack.c:51
[...] kasan_object_err+0x1c/0x70 mm/kasan/report.c:156
[...] print_address_description mm/kasan/report.c:194
[...] kasan_report_error mm/kasan/report.c:283
[...] kasan_report+0x231/0x500 mm/kasan/report.c:303
[...] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:329
[...] kvm_irq_delivery_to_apic_fast+0x11fa/0x1210 arch/x86/kvm/lapic.c:824
[...] kvm_irq_delivery_to_apic+0x132/0x9a0 arch/x86/kvm/irq_comm.c:72
[...] kvm_set_msi+0x111/0x160 arch/x86/kvm/irq_comm.c:157
[...] kvm_send_userspace_msi+0x201/0x280 arch/x86/kvm/../../../virt/kvm/irqchip.c:74
[...] kvm_vm_ioctl+0xba5/0x1670 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3015
[...] vfs_ioctl fs/ioctl.c:43
[...] do_vfs_ioctl+0x18c/0x1040 fs/ioctl.c:679
[...] SYSC_ioctl fs/ioctl.c:694
[...] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
[...] entry_SYSCALL_64_fastpath+0x1f/0xc2
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Cc: stable@vger.kernel.org
Fixes: e45115b62f9a ("KVM: x86: use physical LAPIC array for logical x2APIC")
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>