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BUG: KASAN: use-after-free in ex_handler_refcount+0x164/0x1a0 arch/x86/mm/extable.c:49
Write of size 4 at addr ffff8880903a7c80 by task kworker/u4:6/9354

CPU: 0 PID: 9354 Comm: kworker/u4:6 Not tainted 4.14.229-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: tipc_rcv tipc_recv_work
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x281 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
 kasan_report_error.cold+0x8a/0x191 mm/kasan/report.c:351
 kasan_report mm/kasan/report.c:409 [inline]
 __asan_report_store4_noabort+0x68/0x70 mm/kasan/report.c:434
 ex_handler_refcount+0x164/0x1a0 arch/x86/mm/extable.c:49
 fixup_exception+0x8a/0xd0 arch/x86/mm/extable.c:197
 do_trap_no_signal arch/x86/kernel/traps.c:208 [inline]
 do_trap+0x61/0x250 arch/x86/kernel/traps.c:257
 do_error_trap+0x132/0x2d0 arch/x86/kernel/traps.c:301
 invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:964
RIP: 0010:flags_string.cold+0x6051/0x6a9f
RSP: 0018:ffff888043a0fb78 EFLAGS: 00010283
RAX: ffff888043454400 RBX: ffff8880903a7c80 RCX: ffff8880903a7c80
RDX: 0000000000000000 RSI: 1ffff11008741f62 RDI: ffff8880903a7c80
RBP: ffff8880a772f018 R08: ffffffff8b9cd390 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880903a7c80
R13: ffff8880903a7c88 R14: 0000000000000000 R15: ffff8880a772f000
 tipc_subscrp_subscribe net/tipc/subscr.c:303 [inline]
 tipc_subscrb_rcv_cb+0x5e7/0xa40 net/tipc/subscr.c:338
 tipc_receive_from_sock+0x25c/0x450 net/tipc/server.c:273
 tipc_recv_work+0x75/0xd0 net/tipc/server.c:547
 process_one_work+0x793/0x14a0 kernel/workqueue.c:2116
 worker_thread+0x5cc/0xff0 kernel/workqueue.c:2250
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Allocated by task 9354:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:551
 kmem_cache_alloc_trace+0x131/0x3d0 mm/slab.c:3618
 kmalloc include/linux/slab.h:488 [inline]
 kzalloc include/linux/slab.h:661 [inline]
 tipc_subscrb_create net/tipc/subscr.c:223 [inline]
 tipc_subscrb_connect_cb+0x40/0x150 net/tipc/subscr.c:344
 tipc_accept_from_sock+0x25b/0x400 net/tipc/server.c:313
 tipc_recv_work+0x75/0xd0 net/tipc/server.c:547
 process_one_work+0x793/0x14a0 kernel/workqueue.c:2116
 worker_thread+0x5cc/0xff0 kernel/workqueue.c:2250
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Freed by task 2869:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xc3/0x1a0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xc9/0x250 mm/slab.c:3815
 tipc_subscrb_kref_release net/tipc/subscr.c:155 [inline]
 kref_put include/linux/kref.h:70 [inline]
 tipc_subscrb_put+0x22/0x30 net/tipc/subscr.c:160
 tipc_close_conn+0x16a/0x200 net/tipc/server.c:203
 tipc_send_to_sock net/tipc/server.c:538 [inline]
 tipc_send_work+0x41e/0x520 net/tipc/server.c:564
 process_one_work+0x793/0x14a0 kernel/workqueue.c:2116
 worker_thread+0x5cc/0xff0 kernel/workqueue.c:2250
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

The buggy address belongs to the object at ffff8880903a7c80
 which belongs to the cache kmalloc-96 of size 96
The buggy address is located 0 bytes inside of
 96-byte region [ffff8880903a7c80, ffff8880903a7ce0)
The buggy address belongs to the page:
page:ffffea000240e9c0 count:1 mapcount:0 mapping:ffff8880903a7000 index:0xffff8880903a7700
flags: 0xfff00000000100(slab)
raw: 00fff00000000100 ffff8880903a7000 ffff8880903a7700 0000000100000006
raw: ffffea0002844460 ffffea0002be37e0 ffff88813fe804c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880903a7b80: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff8880903a7c00: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
>ffff8880903a7c80: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
                   ^
 ffff8880903a7d00: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff8880903a7d80: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
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