syzbot


KASAN: stack-out-of-bounds Read in write_mmio

Status: fixed on 2018/01/27 14:55
Subsystems: kvm
[Documentation on labels]
Reported-by: syzbot+b19026412c772c86fca485fc8342e3490da9c269@syzkaller.appspotmail.com
Fix commit: e39d200fa5bf KVM: Fix stack-out-of-bounds read in write_mmio
First crash: 2429d, last: 2415d

Sample crash report:
kvm: KVM_SET_TSS_ADDR need to be called before entering vcpu
==================================================================
BUG: KASAN: stack-out-of-bounds in write_mmio+0x560/0x600 arch/x86/kvm/x86.c:4669
Read of size 8 at addr ffff8801c5b87220 by task syzkaller093882/3155

CPU: 0 PID: 3155 Comm: syzkaller093882 Not tainted 4.15.0-rc2-mm1+ #39
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:53
 print_address_description+0x73/0x250 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report+0x25b/0x340 mm/kasan/report.c:409
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
 write_mmio+0x560/0x600 arch/x86/kvm/x86.c:4669
 emulator_read_write_onepage+0x45a/0xea0 arch/x86/kvm/x86.c:4739
 emulator_read_write+0xe7/0x540 arch/x86/kvm/x86.c:4788
 emulator_write_emulated arch/x86/kvm/x86.c:4825 [inline]
 emulator_fix_hypercall+0x14d/0x1b0 arch/x86/kvm/x86.c:6349
 em_hypercall+0x5d/0x120 arch/x86/kvm/emulate.c:3705
 x86_emulate_insn+0x55d/0x3c20 arch/x86/kvm/emulate.c:5498
 x86_emulate_instruction+0x411/0x1ad0 arch/x86/kvm/x86.c:5756
 emulate_instruction arch/x86/include/asm/kvm_host.h:1177 [inline]
 handle_exception+0x3d5/0xa20 arch/x86/kvm/vmx.c:5921
 vmx_handle_exit+0x25d/0x1ce0 arch/x86/kvm/vmx.c:8887
 vcpu_enter_guest arch/x86/kvm/x86.c:7068 [inline]
 vcpu_run arch/x86/kvm/x86.c:7130 [inline]
 kvm_arch_vcpu_ioctl_run+0x1836/0x5be0 arch/x86/kvm/x86.c:7300
 kvm_vcpu_ioctl+0x64c/0x1010 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2555
 vfs_ioctl fs/ioctl.c:46 [inline]
 do_vfs_ioctl+0x1b1/0x1530 fs/ioctl.c:686
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
 entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x4435c9
RSP: 002b:00007fff805a07d8 EFLAGS: 00000202 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000205b3000 RCX: 00000000004435c9
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
RBP: 000000000000000b R08: 0000000000000000 R09: 0000000000000002
R10: 0000000000000012 R11: 0000000000000202 R12: 00000000205b7e00
R13: 00000000205b6e00 R14: 00000000205b7a00 R15: 00000000205b3000

The buggy address belongs to the page:
page:0000000068f6483a count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x2fffc0000000000()
raw: 02fffc0000000000 0000000000000000 0000000000000000 00000000ffffffff
raw: 0000000000000000 0000000100000001 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801c5b87100: f2 f2 f2 f2 00 f2 f2 f2 f3 f3 f3 f3 00 00 00 00
 ffff8801c5b87180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8801c5b87200: f1 f1 f1 f1 03 f2 f2 f2 f3 f3 f3 f3 00 00 00 00
                               ^
 ffff8801c5b87280: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801c5b87300: 00 f1 f1 f1 f1 02 f2 f2 f2 f2 f2 f2 f2 00 f2 f2
==================================================================

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2017/12/11 20:25 mmots 82bcf1def3b5 da131727 .config console log report syz C ci-upstream-mmots-kasan-gce
2017/12/09 09:14 linux-next ad4dac17f9d5 5ad0ce95 .config console log report syz C ci-upstream-next-kasan-gce
2017/11/27 09:22 upstream 4fbd8d194f06 deb5f6ae .config console log report ci-upstream-kasan-gce-386
* Struck through repros no longer work on HEAD.