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authorRadim Krčmář <rkrcmar@redhat.com>2016-11-22 22:20:14 +0300
committerRadim Krčmář <rkrcmar@redhat.com>2016-11-24 20:35:53 +0300
commit444fdad88f35de9fd1c130b2c4e4550671758fd2 (patch)
tree883df2858855c1686febae12536284805aae8bb5 /arch
parent9c763584b7c8911106bb77af7e648bef09af9d80 (diff)
downloadlinux-444fdad88f35de9fd1c130b2c4e4550671758fd2.tar.xz
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>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kvm/lapic.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 23b99f305382..6f69340f9fa3 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -138,7 +138,7 @@ static inline bool kvm_apic_map_get_logical_dest(struct kvm_apic_map *map,
*mask = dest_id & 0xff;
return true;
case KVM_APIC_MODE_XAPIC_CLUSTER:
- *cluster = map->xapic_cluster_map[dest_id >> 4];
+ *cluster = map->xapic_cluster_map[(dest_id >> 4) & 0xf];
*mask = dest_id & 0xf;
return true;
default: