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BUG: KASAN: use-after-free in atomic_dec_and_test include/asm-generic/atomic-instrumented.h:259 [inline]
BUG: KASAN: use-after-free in put_task_struct include/linux/sched/task.h:95 [inline]
BUG: KASAN: use-after-free in _free_event+0x49a/0x15e0 kernel/events/core.c:4451
Write of size 4 at addr ffff88018c1f0360 by task syz-executor4/12540

CPU: 1 PID: 12540 Comm: syz-executor4 Not tainted 4.18.0+ #197
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c9/0x2b4 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+0x242/0x30d mm/kasan/report.c:412
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
 kasan_check_write+0x14/0x20 mm/kasan/kasan.c:278
 atomic_dec_and_test include/asm-generic/atomic-instrumented.h:259 [inline]
 put_task_struct include/linux/sched/task.h:95 [inline]
 _free_event+0x49a/0x15e0 kernel/events/core.c:4451
 free_event+0xb4/0x180 kernel/events/core.c:4472
 perf_event_release_kernel+0x7d5/0xfc0 kernel/events/core.c:4633
 perf_release+0x37/0x50 kernel/events/core.c:4647
 __fput+0x39b/0x860 fs/file_table.c:251
 ____fput+0x15/0x20 fs/file_table.c:282
 task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x1b25/0x2760 kernel/exit.c:865
 do_group_exit+0x177/0x440 kernel/exit.c:968
 get_signal+0x88e/0x1970 kernel/signal.c:2468
 do_signal+0x9c/0x21c0 arch/x86/kernel/signal.c:816
 exit_to_usermode_loop+0x2e5/0x380 arch/x86/entry/common.c:162
 prepare_exit_to_usermode+0x342/0x3b0 arch/x86/entry/common.c:197
 retint_user+0x8/0x18
RIP: 0033:0x457095
Code: c0 fa ff ff 4c 8b 85 b8 fa ff ff 74 6d 48 8d 42 1e 48 83 e0 f0 48 29 c4 48 8d 44 24 0f 48 83 e0 f0 48 01 d0 48 89 85 18 fb ff <ff> e9 59 fe ff ff 48 8d 42 02 48 89 85 68 fb ff ff 48 89 85 90 fb
RSP: 002b:0000000020000040 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007fcdf3bee6d4 RCX: 0000000000457089
RDX: 0000000020000100 RSI: 0000000020000040 RDI: 0000000000000000
RBP: 00000000009300a0 R08: 0000000020000080 R09: 0000000000000000
R10: 0000000020000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004cb448 R14: 00000000004c3092 R15: 0000000000000000

Allocated by task 12532:
 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
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490
 kmem_cache_alloc_node+0x144/0x780 mm/slab.c:3644
 alloc_task_struct_node kernel/fork.c:157 [inline]
 dup_task_struct kernel/fork.c:802 [inline]
 copy_process.part.36+0x1728/0x7170 kernel/fork.c:1672
 copy_process kernel/fork.c:1647 [inline]
 _do_fork+0x291/0x12a0 kernel/fork.c:2130
 __do_sys_clone kernel/fork.c:2237 [inline]
 __se_sys_clone kernel/fork.c:2231 [inline]
 __x64_sys_clone+0xbf/0x150 kernel/fork.c:2231
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 12532:
 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]
 kmem_cache_free+0x86/0x2d0 mm/slab.c:3756
 free_task_struct kernel/fork.c:162 [inline]
 free_task+0x16e/0x1f0 kernel/fork.c:415
 copy_process.part.36+0x163c/0x7170 kernel/fork.c:2065
 copy_process kernel/fork.c:1647 [inline]
 _do_fork+0x291/0x12a0 kernel/fork.c:2130
 __do_sys_clone kernel/fork.c:2237 [inline]
 __se_sys_clone kernel/fork.c:2231 [inline]
 __x64_sys_clone+0xbf/0x150 kernel/fork.c:2231
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff88018c1f0340
 which belongs to the cache task_struct(65:syz4) of size 5952
The buggy address is located 32 bytes inside of
 5952-byte region [ffff88018c1f0340, ffff88018c1f1a80)
The buggy address belongs to the page:
page:ffffea0006307c00 count:1 mapcount:0 mapping:ffff8801d79ec600 index:0x0 compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffffea0006566c88 ffffea0006ab1d88 ffff8801d79ec600
raw: 0000000000000000 ffff88018c1f0340 0000000100000001 ffff8801c82f4440
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff8801c82f4440

Memory state around the buggy address:
 ffff88018c1f0200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88018c1f0280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88018c1f0300: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
                                                       ^
 ffff88018c1f0380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88018c1f0400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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