This is a note to let you know that I've just added the patch titled
KVM: x86: fix out-of-bounds access in lapic
to the 4.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-x86-fix-out-of-bounds-access-in-lapic.patch
and it can be found in the queue-4.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 444fdad88f35de9fd1c130b2c4e4550671758fd2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= <rkrcmar@xxxxxxxxxx>
Date: Tue, 22 Nov 2016 20:20:14 +0100
Subject: KVM: x86: fix out-of-bounds access in lapic
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From: Radim Krčmář <rkrcmar@xxxxxxxxxx>
commit 444fdad88f35de9fd1c130b2c4e4550671758fd2 upstream.
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@xxxxxxxxxx>
Fixes: e45115b62f9a ("KVM: x86: use physical LAPIC array for logical x2APIC")
Reviewed-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Radim Krčmář <rkrcmar@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/lapic.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -138,7 +138,7 @@ static inline bool kvm_apic_map_get_logi
*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:
Patches currently in stable-queue which might be from rkrcmar@xxxxxxxxxx are
queue-4.8/kvm-x86-fix-out-of-bounds-access-in-lapic.patch
queue-4.8/kvm-x86-check-for-pic-and-ioapic-presence-before-use.patch
queue-4.8/kvm-x86-fix-out-of-bounds-accesses-of-rtc_eoi-map.patch
queue-4.8/kvm-x86-drop-error-recovery-in-em_jmp_far-and-em_ret_far.patch
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