Date:   Mon, 30 Oct 2017 12:12:04 -0700
From:   syzbot 
        <bot+7ad82526b98c64c90062275162dacfa48c20dbd3@...kaller.appspotmail.com>
To:     borntraeger@...ibm.com, cornelia.huck@...ibm.com, david@...hat.com,
        hpa@...or.com, jschoenh@...zon.de, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, mingo@...hat.com,
        pbonzini@...hat.com, rkrcmar@...hat.com,
        syzkaller-bugs@...glegroups.com, tglx@...utronix.de, x86@...nel.org
Subject: KASAN: use-after-free Write in irq_bypass_register_consumer

Hello,

syzkaller hit the following crash on  
cd4175b11685b11c40e31a03e05084cc212b0649
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.

syzkaller reproducer is attached. See https://goo.gl/kgGztJ
for information about syzkaller reproducers


BUG: KASAN: use-after-free in __list_add include/linux/list.h:63 [inline]
BUG: KASAN: use-after-free in list_add include/linux/list.h:78 [inline]
BUG: KASAN: use-after-free in irq_bypass_register_consumer+0x4b4/0x500  
virt/lib/irqbypass.c:217
Write of size 8 at addr ffff8801c994a240 by task syz-executor0/4607

CPU: 0 PID: 4607 Comm: syz-executor0 Not tainted 4.14.0-rc1+ #8
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:16 [inline]
  dump_stack+0x194/0x257 lib/dump_stack.c:52
  print_address_description+0x73/0x250 mm/kasan/report.c:252
  kasan_report_error mm/kasan/report.c:351 [inline]
  kasan_report+0x24e/0x340 mm/kasan/report.c:409
  __asan_report_store8_noabort+0x17/0x20 mm/kasan/report.c:435
  __list_add include/linux/list.h:63 [inline]
  list_add include/linux/list.h:78 [inline]
  irq_bypass_register_consumer+0x4b4/0x500 virt/lib/irqbypass.c:217
  kvm_irqfd_assign arch/x86/kvm/../../../virt/kvm/eventfd.c:417 [inline]
  kvm_irqfd+0x137a/0x1d50 arch/x86/kvm/../../../virt/kvm/eventfd.c:572
  kvm_vm_ioctl+0x1079/0x1c40 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2991
  kvm_vm_compat_ioctl+0x2ed/0x3e0  
arch/x86/kvm/../../../virt/kvm/kvm_main.c:3135
  C_SYSC_ioctl fs/compat_ioctl.c:1593 [inline]
  compat_SyS_ioctl+0x1da/0x3300 fs/compat_ioctl.c:1540
  do_syscall_32_irqs_on arch/x86/entry/common.c:329 [inline]
  do_fast_syscall_32+0x3f2/0xeed arch/x86/entry/common.c:391
  entry_SYSENTER_compat+0x51/0x60 arch/x86/entry/entry_64_compat.S:124
RIP: 0023:0xf7f5ac79
RSP: 002b:00000000f7f5605c EFLAGS: 00000296 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000009 RCX: 000000004020ae76
RDX: 0000000020025fe0 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 4607:
  save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
  save_stack+0x43/0xd0 mm/kasan/kasan.c:447
  set_track mm/kasan/kasan.c:459 [inline]
  kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
  kmem_cache_alloc_trace+0x136/0x750 mm/slab.c:3627
  kmalloc include/linux/slab.h:493 [inline]
  kzalloc include/linux/slab.h:666 [inline]
  kvm_irqfd_assign arch/x86/kvm/../../../virt/kvm/eventfd.c:296 [inline]
  kvm_irqfd+0x16c/0x1d50 arch/x86/kvm/../../../virt/kvm/eventfd.c:572
  kvm_vm_ioctl+0x1079/0x1c40 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2991
  kvm_vm_compat_ioctl+0x2ed/0x3e0  
arch/x86/kvm/../../../virt/kvm/kvm_main.c:3135
  C_SYSC_ioctl fs/compat_ioctl.c:1593 [inline]
  compat_SyS_ioctl+0x1da/0x3300 fs/compat_ioctl.c:1540
  do_syscall_32_irqs_on arch/x86/entry/common.c:329 [inline]
  do_fast_syscall_32+0x3f2/0xeed arch/x86/entry/common.c:391
  entry_SYSENTER_compat+0x51/0x60 arch/x86/entry/entry_64_compat.S:124

Freed by task 23:
  save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
  save_stack+0x43/0xd0 mm/kasan/kasan.c:447
  set_track mm/kasan/kasan.c:459 [inline]
  kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
  __cache_free mm/slab.c:3503 [inline]
  kfree+0xca/0x250 mm/slab.c:3820
  irqfd_shutdown+0x13c/0x1a0 arch/x86/kvm/../../../virt/kvm/eventfd.c:148
  process_one_work+0xbfa/0x1bd0 kernel/workqueue.c:2119
  worker_thread+0x223/0x1860 kernel/workqueue.c:2253
  kthread+0x39c/0x470 kernel/kthread.c:231
  ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431

The buggy address belongs to the object at ffff8801c994a0c0
  which belongs to the cache kmalloc-512 of size 512
The buggy address is located 384 bytes inside of
  512-byte region [ffff8801c994a0c0, ffff8801c994a2c0)
The buggy address belongs to the page:
page:ffffea0007265280 count:1 mapcount:0 mapping:ffff8801c994a0c0  
index:0xffff8801c994ad40
flags: 0x200000000000100(slab)
raw: 0200000000000100 ffff8801c994a0c0 ffff8801c994ad40 0000000100000001
raw: ffffea0007265320 ffffea00072630e0 ffff8801dac00940 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff8801c994a100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff8801c994a180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8801c994a200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                            ^
  ffff8801c994a280: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
  ffff8801c994a300: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
==================================================================


---
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