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BUG: KASAN: use-after-free in relay_switch_subbuf+0x8be/0x920 kernel/relay.c:755
Read of size 8 at addr ffff888095228318 by task swapper/1/0

CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.3.0-rc6+ #147
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+0x172/0x1f0 lib/dump_stack.c:113
 print_address_description.cold+0xd4/0x306 mm/kasan/report.c:351
 __kasan_report.cold+0x1b/0x36 mm/kasan/report.c:482
 kasan_report+0x12/0x17 mm/kasan/common.c:618
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
 relay_switch_subbuf+0x8be/0x920 kernel/relay.c:755
 relay_reserve include/linux/relay.h:261 [inline]
 trace_note.isra.0+0x5b8/0x6e0 kernel/trace/blktrace.c:93
 trace_note_tsk kernel/trace/blktrace.c:124 [inline]
 __blk_add_trace+0xb70/0xe10 kernel/trace/blktrace.c:264
 blk_add_trace_rq+0x185/0x1f0 kernel/trace/blktrace.c:813
 blk_add_trace_rq_complete+0x17a/0x1e0 kernel/trace/blktrace.c:842
 trace_block_rq_complete include/trace/events/block.h:116 [inline]
 blk_update_request+0x851/0xc10 block/blk-core.c:1403
 scsi_end_request+0x7f/0x840 drivers/scsi/scsi_lib.c:579
 scsi_io_completion+0x20a/0x1420 drivers/scsi/scsi_lib.c:963
 scsi_finish_command+0x3b7/0x670 drivers/scsi/scsi.c:228
 scsi_softirq_done+0x326/0x3b0 drivers/scsi/scsi_lib.c:1465
 blk_done_softirq+0x2fe/0x4d0 block/blk-softirq.c:37
 __do_softirq+0x262/0x98c kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0x19b/0x1e0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:537 [inline]
 do_IRQ+0x12c/0x200 arch/x86/kernel/irq.c:259
 common_interrupt+0xf/0xf arch/x86/entry/entry_64.S:607
 </IRQ>
RIP: 0010:native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:61
Code: 48 c2 6e fa eb 8a 90 90 90 90 90 90 e9 07 00 00 00 0f 00 2d 04 6d 4a 00 f4 c3 66 90 e9 07 00 00 00 0f 00 2d f4 6c 4a 00 fb f4 <c3> 90 55 48 89 e5 41 57 41 56 41 55 41 54 53 e8 6e 83 22 fa e8 29
RSP: 0018:ffff8880a98dfd68 EFLAGS: 00000286 ORIG_RAX: ffffffffffffffdd
RAX: 1ffffffff11a5e8d RBX: ffff8880a98c6340 RCX: 1ffffffff134b5de
RDX: dffffc0000000000 RSI: ffffffff8177f03e RDI: ffffffff873db36c
RBP: ffff8880a98dfd98 R08: ffff8880a98c6340 R09: ffffed1015318c69
R10: ffffed1015318c68 R11: ffff8880a98c6347 R12: dffffc0000000000
R13: ffffffff89a57cf8 R14: 0000000000000000 R15: 0000000000000001
 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:571
 default_idle_call+0x84/0xb0 kernel/sched/idle.c:94
 cpuidle_idle_call kernel/sched/idle.c:154 [inline]
 do_idle+0x413/0x760 kernel/sched/idle.c:263
 cpu_startup_entry+0x1b/0x20 kernel/sched/idle.c:354
 start_secondary+0x315/0x430 arch/x86/kernel/smpboot.c:264
 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:241

Allocated by task 9831:
 save_stack+0x23/0x90 mm/kasan/common.c:69
 set_track mm/kasan/common.c:77 [inline]
 __kasan_kmalloc mm/kasan/common.c:493 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:466
 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:501
 slab_post_alloc_hook mm/slab.h:520 [inline]
 slab_alloc mm/slab.c:3319 [inline]
 kmem_cache_alloc+0x121/0x710 mm/slab.c:3483
 __d_alloc+0x2e/0x8c0 fs/dcache.c:1688
 d_alloc+0x4d/0x280 fs/dcache.c:1767
 __lookup_hash+0xcd/0x190 fs/namei.c:1540
 filename_create+0x1a7/0x4f0 fs/namei.c:3635
 user_path_create fs/namei.c:3692 [inline]
 do_mkdirat+0xb5/0x2a0 fs/namei.c:3830
 __do_sys_mkdir fs/namei.c:3854 [inline]
 __se_sys_mkdir fs/namei.c:3852 [inline]
 __x64_sys_mkdir+0x5c/0x80 fs/namei.c:3852
 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 9831:
 save_stack+0x23/0x90 mm/kasan/common.c:69
 set_track mm/kasan/common.c:77 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:455
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:463
 __cache_free mm/slab.c:3425 [inline]
 kmem_cache_free+0x86/0x320 mm/slab.c:3693
 __d_free+0x20/0x30 fs/dcache.c:271
 __rcu_reclaim kernel/rcu/rcu.h:222 [inline]
 rcu_do_batch kernel/rcu/tree.c:2114 [inline]
 rcu_core+0x67f/0x1580 kernel/rcu/tree.c:2314
 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2323
 __do_softirq+0x262/0x98c kernel/softirq.c:292

The buggy address belongs to the object at ffff8880952282c0
 which belongs to the cache dentry(17:syz0) of size 288
The buggy address is located 88 bytes inside of
 288-byte region [ffff8880952282c0, ffff8880952283e0)
The buggy address belongs to the page:
page:ffffea0002548a00 refcount:1 mapcount:0 mapping:ffff88809b482000 index:0x0
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea00024b0108 ffffea0000318808 ffff88809b482000
raw: 0000000000000000 ffff888095228000 000000010000000b 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888095228200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888095228280: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff888095228300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff888095228380: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff888095228400: fc fc fc fc fb fb fb fb fb fb fb fb fb fb fb fb
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