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BUG: KASAN: use-after-free in dev_expire_timer+0x414/0x570 drivers/isdn/mISDN/timerdev.c:174
Read of size 8 at addr ffff88809fd76cd0 by task syz-executor1/18425

CPU: 1 PID: 18425 Comm: syz-executor1 Not tainted 4.20.0+ #4
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1db/0x2d0 lib/dump_stack.c:113
 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:187
 kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135
 dev_expire_timer+0x414/0x570 drivers/isdn/mISDN/timerdev.c:174
 call_timer_fn+0x254/0x900 kernel/time/timer.c:1325
 expire_timers kernel/time/timer.c:1362 [inline]
 __run_timers+0x6fc/0xd50 kernel/time/timer.c:1681
 run_timer_softirq+0x52/0xb0 kernel/time/timer.c:1694
 __do_softirq+0x30b/0xb11 kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0x180/0x1d0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:536 [inline]
 smp_apic_timer_interrupt+0x1b7/0x760 arch/x86/kernel/apic/apic.c:1062
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:807
 </IRQ>
RIP: 0010:memset_erms+0x9/0x10 arch/x86/lib/memset_64.S:66
Code: c1 e9 03 40 0f b6 f6 48 b8 01 01 01 01 01 01 01 01 48 0f af c6 f3 48 ab 89 d1 f3 aa 4c 89 c8 c3 90 49 89 f9 40 88 f0 48 89 d1 <f3> aa 4c 89 c8 c3 90 49 89 fa 40 0f b6 ce 48 b8 01 01 01 01 01 01
RSP: 0000:ffff8880531e7118 EFLAGS: 00010206 ORIG_RAX: ffffffffffffff13
RAX: 1ffff11007b40000 RBX: ffffed1007b40000 RCX: 0000000000005e40
RDX: 0000000000040000 RSI: 0000000000000000 RDI: ffffed1007b3a1c0
RBP: ffff8880531e7130 R08: ffff88805a594600 R09: ffffed1007b00000
R10: fffff940001ec006 R11: ffffea0000f60037 R12: 0000000000200000
R13: dffffc0000000000 R14: dffffc0000000000 R15: dffffc0000000000
 kasan_alloc_pages+0x38/0x40 mm/kasan/common.c:233
 post_alloc_hook mm/page_alloc.c:1949 [inline]
 prep_new_page mm/page_alloc.c:1958 [inline]
 get_page_from_freelist+0xc7f/0x5190 mm/page_alloc.c:3494
 __alloc_pages_nodemask+0x4fd/0xdc0 mm/page_alloc.c:4529
 __alloc_pages include/linux/gfp.h:473 [inline]
 __alloc_pages_node include/linux/gfp.h:486 [inline]
 alloc_pages_vma+0x39a/0x540 mm/mempolicy.c:2062
 do_huge_pmd_anonymous_page+0x53a/0x1840 mm/huge_memory.c:738
 create_huge_pmd mm/memory.c:3657 [inline]
 __handle_mm_fault+0x38e7/0x5690 mm/memory.c:3861
 handle_mm_fault+0x4ec/0xc80 mm/memory.c:3927
 do_user_addr_fault arch/x86/mm/fault.c:1475 [inline]
 __do_page_fault+0x5da/0xd60 arch/x86/mm/fault.c:1541
 do_page_fault+0xe6/0x7d8 arch/x86/mm/fault.c:1572
 page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1143
RIP: 0033:0x43f1c1
Code: 8d 15 23 54 0a 00 8b 0c 8a 8b 04 82 29 c8 c3 66 2e 0f 1f 84 00 00 00 00 00 48 83 fa 20 48 89 f8 73 77 f6 c2 01 74 0b 0f b6 0e <88> 0f 48 ff c6 48 ff c7 f6 c2 02 74 12 0f b7 0e 66 89 0f 48 83 c6
RSP: 002b:00007ffcf3a17428 EFLAGS: 00010202
RAX: 0000000020042000 RBX: 0000000000000003 RCX: 000000000000002f
RDX: 000000000000000d RSI: 0000000000740020 RDI: 0000000020042000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000004
R10: 0000000000000075 R11: 0000000000000246 R12: 0000000000000000
R13: fffffffffffffffe R14: 000000000000005c R15: 0000000000000001

Allocated by task 18426:
 save_stack+0x45/0xd0 mm/kasan/common.c:73
 set_track mm/kasan/common.c:85 [inline]
 kasan_kmalloc mm/kasan/common.c:482 [inline]
 kasan_kmalloc+0xcf/0xe0 mm/kasan/common.c:455
 kmem_cache_alloc_trace+0x151/0x760 mm/slab.c:3607
 kmalloc include/linux/slab.h:545 [inline]
 kzalloc include/linux/slab.h:740 [inline]
 misdn_add_timer drivers/isdn/mISDN/timerdev.c:188 [inline]
 mISDN_ioctl+0x544/0xc40 drivers/isdn/mISDN/timerdev.c:242
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:509 [inline]
 do_vfs_ioctl+0x107b/0x17d0 fs/ioctl.c:696
 ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
 __do_sys_ioctl fs/ioctl.c:720 [inline]
 __se_sys_ioctl fs/ioctl.c:718 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 18423:
 save_stack+0x45/0xd0 mm/kasan/common.c:73
 set_track mm/kasan/common.c:85 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:444
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:452
 __cache_free mm/slab.c:3485 [inline]
 kfree+0xcf/0x230 mm/slab.c:3804
 mISDN_close+0x375/0x530 drivers/isdn/mISDN/timerdev.c:95
 __fput+0x3c5/0xb10 fs/file_table.c:278
 ____fput+0x16/0x20 fs/file_table.c:309
 task_work_run+0x1f4/0x2b0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x32a/0x3b0 arch/x86/entry/common.c:166
 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
 do_syscall_64+0x696/0x800 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff88809fd76cc0
 which belongs to the cache kmalloc-128 of size 128
The buggy address is located 16 bytes inside of
 128-byte region [ffff88809fd76cc0, ffff88809fd76d40)
The buggy address belongs to the page:
page:ffffea00027f5d80 count:1 mapcount:0 mapping:ffff88812c3f0640 index:0x0
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea000279f148 ffffea00026e6788 ffff88812c3f0640
raw: 0000000000000000 ffff88809fd76000 0000000100000015 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809fd76b80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff88809fd76c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88809fd76c80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
                                                 ^
 ffff88809fd76d00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff88809fd76d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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