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BUG: KASAN: use-after-free in relay_switch_subbuf+0x8c0/0x930 kernel/relay.c:755
Read of size 8 at addr ffff88805ac45358 by task kworker/u4:9/12178

CPU: 1 PID: 12178 Comm: kworker/u4:9 Not tainted 5.0.0-rc7+ #80
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: bat_events batadv_nc_worker
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 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
 relay_switch_subbuf+0x8c0/0x930 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:818
 blk_add_trace_rq_complete+0x17a/0x1e0 kernel/trace/blktrace.c:847
 trace_block_rq_complete include/trace/events/block.h:116 [inline]
 blk_update_request+0x7bc/0xb50 block/blk-core.c:1437
 scsi_end_request+0x82/0x8d0 drivers/scsi/scsi_lib.c:587
 scsi_io_completion+0x259/0x1820 drivers/scsi/scsi_lib.c:993
 scsi_finish_command+0x3ba/0x670 drivers/scsi/scsi.c:248
 scsi_softirq_done+0x344/0x3e0 drivers/scsi/scsi_lib.c:1499
 blk_done_softirq+0x304/0x4d0 block/blk-softirq.c:37
 __do_softirq+0x266/0x95a 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]
 do_IRQ+0x114/0x1d0 arch/x86/kernel/irq.c:258
 common_interrupt+0xf/0xf arch/x86/entry/entry_64.S:583
 </IRQ>
RIP: 0010:should_resched arch/x86/include/asm/preempt.h:102 [inline]
RIP: 0010:__local_bh_enable_ip+0x18e/0x270 kernel/softirq.c:196
Code: 00 00 00 00 fc ff df 48 c1 e8 03 80 3c 10 00 0f 85 df 00 00 00 48 83 3d bf c0 4d 07 00 0f 84 8f 00 00 00 fb 66 0f 1f 44 00 00 <65> 8b 05 7b 2b bd 7e 85 c0 74 7f 5b 41 5c 41 5d 5d c3 80 3d ce 16
RSP: 0018:ffff88806ccffc20 EFLAGS: 00000286 ORIG_RAX: ffffffffffffffdd
RAX: 1ffffffff1125060 RBX: 0000000000000201 RCX: 1ffff1100d762d99
RDX: dffffc0000000000 RSI: ffff88806bb16ca8 RDI: ffff88806bb16c7c
RBP: ffff88806ccffc38 R08: ffff88806bb16400 R09: ffff88806bb16cc8
R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff86e70897
R13: ffff88806bb16400 R14: ffffffff86e711c0 R15: 000000000000002b
 __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:176 [inline]
 _raw_spin_unlock_bh+0x31/0x40 kernel/locking/spinlock.c:200
 spin_unlock_bh include/linux/spinlock.h:374 [inline]
 batadv_nc_purge_paths+0x267/0x370 net/batman-adv/network-coding.c:482
 batadv_nc_worker+0x2cf/0x760 net/batman-adv/network-coding.c:733
 process_one_work+0x98e/0x1790 kernel/workqueue.c:2173
 worker_thread+0x98/0xe40 kernel/workqueue.c:2319
 kthread+0x357/0x430 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

Allocated by task 26432:
 save_stack+0x45/0xd0 mm/kasan/common.c:73
 set_track mm/kasan/common.c:85 [inline]
 __kasan_kmalloc mm/kasan/common.c:496 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:469
 kasan_kmalloc mm/kasan/common.c:504 [inline]
 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:411
 kmem_cache_alloc+0x12d/0x710 mm/slab.c:3543
 __d_alloc+0x2e/0x8c0 fs/dcache.c:1622
 d_alloc+0x4d/0x2b0 fs/dcache.c:1701
 __lookup_hash+0xcd/0x190 fs/namei.c:1542
 filename_create+0x1a7/0x4f0 fs/namei.c:3636
 user_path_create fs/namei.c:3693 [inline]
 do_symlinkat+0xf3/0x290 fs/namei.c:4146
 __do_sys_symlink fs/namei.c:4172 [inline]
 __se_sys_symlink fs/namei.c:4170 [inline]
 __x64_sys_symlink+0x59/0x80 fs/namei.c:4170
 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 16:
 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:458
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:466
 __cache_free mm/slab.c:3487 [inline]
 kmem_cache_free+0x86/0x260 mm/slab.c:3749
 __d_free+0x20/0x30 fs/dcache.c:269
 __rcu_reclaim kernel/rcu/rcu.h:240 [inline]
 rcu_do_batch kernel/rcu/tree.c:2452 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2773 [inline]
 rcu_process_callbacks+0x928/0x1390 kernel/rcu/tree.c:2754
 __do_softirq+0x266/0x95a kernel/softirq.c:292

The buggy address belongs to the object at ffff88805ac45300
 which belongs to the cache dentry(65:syz3) of size 288
The buggy address is located 88 bytes inside of
 288-byte region [ffff88805ac45300, ffff88805ac45420)
The buggy address belongs to the page:
page:ffffea00016b1140 count:1 mapcount:0 mapping:ffff88809533c6c0 index:0x0
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea0002275348 ffffea00017a3788 ffff88809533c6c0
raw: 0000000000000000 ffff88805ac45040 000000010000000b ffff888069622680
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff888069622680

Memory state around the buggy address:
 ffff88805ac45200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88805ac45280: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
>ffff88805ac45300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                    ^
 ffff88805ac45380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88805ac45400: fb fb fb fb fc fc fc fc fc fc fc fc fb fb fb fb
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