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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 ffff888087e1b258 by task kworker/1:2/2700

CPU: 1 PID: 2700 Comm: kworker/1:2 Not tainted 4.14.192-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events do_enable_set
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x283 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
 kasan_report_error.cold+0x8a/0x194 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/0xc3 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:inat_get_avx_attribute+0x52f2/0x6a9a
RSP: 0018:ffff88809f827c88 EFLAGS: 00010297
RAX: ffff88809fd5c340 RBX: 0000000000000001 RCX: ffff888087e1b258
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff888087e1b240
RBP: ffff888087e1b240 R08: ffffffff8a07b358 R09: 000000000004057a
R10: ffff88809fd5cbf0 R11: ffff88809fd5c340 R12: ffff8880971c5c10
R13: ffff88809ff7bf00 R14: ffff8880aeb2ad00 R15: ffff8880971c5c00
 do_enable_set+0x47f/0x8a0 net/bluetooth/6lowpan.c:1087
 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 2700:
 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]
 l2cap_chan_create+0x3e/0x3c0 net/bluetooth/l2cap_core.c:441
 chan_create net/bluetooth/6lowpan.c:652 [inline]
 bt_6lowpan_listen net/bluetooth/6lowpan.c:971 [inline]
 do_enable_set+0x4ac/0x8a0 net/bluetooth/6lowpan.c:1090
 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 3653:
 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
 l2cap_chan_destroy net/bluetooth/l2cap_core.c:479 [inline]
 kref_put include/linux/kref.h:70 [inline]
 l2cap_chan_put+0x152/0x1b0 net/bluetooth/l2cap_core.c:493
 do_enable_set+0x47f/0x8a0 net/bluetooth/6lowpan.c:1087
 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 ffff888087e1b240
 which belongs to the cache kmalloc-2048 of size 2048
The buggy address is located 24 bytes inside of
 2048-byte region [ffff888087e1b240, ffff888087e1ba40)
The buggy address belongs to the page:
page:ffffea00021f8680 count:1 mapcount:0 mapping:ffff888087e1a140 index:0x0 compound_mapcount: 0
flags: 0xfffe0000008100(slab|head)
raw: 00fffe0000008100 ffff888087e1a140 0000000000000000 0000000100000003
raw: ffffea00025cc620 ffffea00025bdf20 ffff88812fe52c40 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888087e1b100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888087e1b180: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff888087e1b200: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
                                                    ^
 ffff888087e1b280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888087e1b300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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