==================================================================
BUG: KASAN: use-after-free in irq_bypass_register_consumer+0x4b1/0x530 virt/lib/irqbypass.c:198
Read of size 8 at addr ffff8801b059e1b8 by task syz-executor6/17395

CPU: 1 PID: 17395 Comm: syz-executor6 Not tainted 4.17.0+ #119
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
sctp: [Deprecated]: syz-executor4 (pid 17407) Use of int in maxseg socket option.
Use struct sctp_assoc_value instead
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1b9/0x294 lib/dump_stack.c:113
 print_address_description+0x6c/0x20b mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 irq_bypass_register_consumer+0x4b1/0x530 virt/lib/irqbypass.c:198
 kvm_irqfd_assign arch/x86/kvm/../../../virt/kvm/eventfd.c:417 [inline]
 kvm_irqfd+0x14f6/0x1e60 arch/x86/kvm/../../../virt/kvm/eventfd.c:572
sctp: [Deprecated]: syz-executor4 (pid 17407) Use of int in maxseg socket option.
Use struct sctp_assoc_value instead
 kvm_vm_ioctl+0xf84/0x1d90 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2997
 kvm_vm_compat_ioctl+0x13b/0x420 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3141
 __do_compat_sys_ioctl fs/compat_ioctl.c:1459 [inline]
 __se_compat_sys_ioctl fs/compat_ioctl.c:1405 [inline]
 __ia32_compat_sys_ioctl+0x221/0x640 fs/compat_ioctl.c:1405
 do_syscall_32_irqs_on arch/x86/entry/common.c:323 [inline]
 do_fast_syscall_32+0x345/0xf9b arch/x86/entry/common.c:394
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7f3bcb9
Code: 55 08 8b 88 64 cd ff ff 8b 98 68 cd ff ff 89 c8 85 d2 74 02 89 0a 5b 5d c3 8b 04 24 c3 8b 1c 24 c3 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90 
RSP: 002b:00000000f5f370ac EFLAGS: 00000282 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000019 RCX: 000000004020ae76
RDX: 0000000020000180 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 17395:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
 kmem_cache_alloc_trace+0x152/0x780 mm/slab.c:3620
 kmalloc include/linux/slab.h:513 [inline]
 kzalloc include/linux/slab.h:706 [inline]
 kvm_irqfd_assign arch/x86/kvm/../../../virt/kvm/eventfd.c:296 [inline]
 kvm_irqfd+0x187/0x1e60 arch/x86/kvm/../../../virt/kvm/eventfd.c:572
 kvm_vm_ioctl+0xf84/0x1d90 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2997
 kvm_vm_compat_ioctl+0x13b/0x420 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3141
 __do_compat_sys_ioctl fs/compat_ioctl.c:1459 [inline]
 __se_compat_sys_ioctl fs/compat_ioctl.c:1405 [inline]
 __ia32_compat_sys_ioctl+0x221/0x640 fs/compat_ioctl.c:1405
 do_syscall_32_irqs_on arch/x86/entry/common.c:323 [inline]
 do_fast_syscall_32+0x345/0xf9b arch/x86/entry/common.c:394
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139

Freed by task 11107:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3498 [inline]
 kfree+0xd9/0x260 mm/slab.c:3813
 irqfd_shutdown+0x13a/0x1a0 arch/x86/kvm/../../../virt/kvm/eventfd.c:148
 process_one_work+0xc64/0x1b70 kernel/workqueue.c:2153
 worker_thread+0x181/0x13a0 kernel/workqueue.c:2296
 kthread+0x345/0x410 kernel/kthread.c:240
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412

The buggy address belongs to the object at ffff8801b059e040
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 376 bytes inside of
 512-byte region [ffff8801b059e040, ffff8801b059e240)
The buggy address belongs to the page:
page:ffffea0006c16780 count:1 mapcount:0 mapping:ffff8801da800940 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffffea00073ae108 ffffea0006f5dfc8 ffff8801da800940
raw: 0000000000000000 ffff8801b059e040 0000000100000006 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801b059e080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801b059e100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8801b059e180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                        ^
 ffff8801b059e200: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8801b059e280: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
==================================================================