==================================================================
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/0x1610 kernel/events/core.c:4452
Write of size 4 at addr ffff88018adaa0a0 by task syz-executor4/9277

CPU: 0 PID: 9277 Comm: syz-executor4 Not tainted 4.19.0-rc6+ #41
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+0x1c4/0x2b4 lib/dump_stack.c:113
 print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.9+0x242/0x309 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/0x1610 kernel/events/core.c:4452
 free_event+0xb4/0x180 kernel/events/core.c:4473
 perf_event_release_kernel+0x7d8/0xfa0 kernel/events/core.c:4634
 perf_release+0x37/0x50 kernel/events/core.c:4648
 __fput+0x385/0xa30 fs/file_table.c:278
 ____fput+0x15/0x20 fs/file_table.c:309
 task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x1ad7/0x2610 kernel/exit.c:867
 do_group_exit+0x177/0x440 kernel/exit.c:970
 get_signal+0x8b0/0x1980 kernel/signal.c:2513
 do_signal+0x9c/0x21e0 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:          (null)
Code: Bad RIP value.
RSP: 002b:0000000020000188 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 0000000000000005 RCX: 0000000000457579
RDX: 0000000020000080 RSI: 0000000020000180 RDI: 0000000000000000
RBP: 000000000072bf00 R08: 0000000020000240 R09: 0000000000000000
R10: 0000000020000040 R11: 0000000000000246 R12: 00007f5cc9fcd6d4
R13: 00000000004bd9fa R14: 00000000004cc448 R15: 00000000ffffffff

Allocated by task 9266:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490
 kmem_cache_alloc_node+0x144/0x730 mm/slab.c:3644
 alloc_task_struct_node kernel/fork.c:157 [inline]
 dup_task_struct kernel/fork.c:802 [inline]
 copy_process+0x1ff4/0x8780 kernel/fork.c:1707
 _do_fork+0x1cb/0x11d0 kernel/fork.c:2166
 __do_sys_clone kernel/fork.c:2273 [inline]
 __se_sys_clone kernel/fork.c:2267 [inline]
 __x64_sys_clone+0xbf/0x150 kernel/fork.c:2267
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 9266:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x102/0x150 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+0x83/0x290 mm/slab.c:3756
 free_task_struct kernel/fork.c:162 [inline]
 free_task+0x16e/0x1f0 kernel/fork.c:416
 copy_process+0x1d9a/0x8780 kernel/fork.c:2098
 _do_fork+0x1cb/0x11d0 kernel/fork.c:2166
 __do_sys_clone kernel/fork.c:2273 [inline]
 __se_sys_clone kernel/fork.c:2267 [inline]
 __x64_sys_clone+0xbf/0x150 kernel/fork.c:2267
 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 ffff88018adaa080
 which belongs to the cache task_struct(81:syz4) of size 6080
The buggy address is located 32 bytes inside of
 6080-byte region [ffff88018adaa080, ffff88018adab840)
The buggy address belongs to the page:
page:ffffea00062b6a80 count:1 mapcount:0 mapping:ffff8801d25b2980 index:0x0 compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffffea00062b6a08 ffffea00074c1408 ffff8801d25b2980
raw: 0000000000000000 ffff88018adaa080 0000000100000001 ffff8801b9cda140
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff8801b9cda140

Memory state around the buggy address:
 ffff88018ada9f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88018adaa000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88018adaa080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff88018adaa100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88018adaa180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
raw_sendmsg: syz-executor0 forgot to set AF_INET. Fix it!
FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 0
CPU: 1 PID: 9303 Comm: syz-executor2 Tainted: G    B             4.19.0-rc6+ #41
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+0x1c4/0x2b4 lib/dump_stack.c:113
 fail_dump lib/fault-inject.c:51 [inline]
 should_fail.cold.4+0xa/0x17 lib/fault-inject.c:149
 __should_failslab+0x124/0x180 mm/failslab.c:32
 should_failslab+0x9/0x14 mm/slab_common.c:1557
 slab_pre_alloc_hook mm/slab.h:423 [inline]
 slab_alloc mm/slab.c:3378 [inline]
 __do_kmalloc mm/slab.c:3716 [inline]
 __kmalloc+0x2d4/0x760 mm/slab.c:3727
 kmalloc_array include/linux/slab.h:635 [inline]
 rw_copy_check_uvector+0x364/0x3e0 fs/read_write.c:781
 import_iovec+0xcf/0x470 lib/iov_iter.c:1528
 vfs_readv+0xf5/0x1c0 fs/read_write.c:984
 do_preadv+0x1cc/0x280 fs/read_write.c:1070
 __do_sys_preadv fs/read_write.c:1120 [inline]
 __se_sys_preadv fs/read_write.c:1115 [inline]
 __x64_sys_preadv+0x9a/0xf0 fs/read_write.c:1115
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457579
Code: 1d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 eb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fb1ca009c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 00007fb1ca009c90 RCX: 0000000000457579
RDX: 10000000000001ed RSI: 0000000020000480 RDI: 0000000000000004
RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 000000004c000000 R11: 0000000000000246 R12: 00007fb1ca00a6d4
R13: 00000000004c309c R14: 00000000004d4a40 R15: 0000000000000005