syzbot

batman_adv: batadv0: Interface activated: batadv_slave_1
IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready
==================================================================
BUG: KASAN: use-after-free in hci_conn_del+0x5c7/0x620 net/bluetooth/hci_conn.c:596
Write of size 8 at addr ffff8880856e5708 by task syz-executor.3/6381

CPU: 1 PID: 6381 Comm: syz-executor.3 Not tainted 4.14.193-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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_store8_noabort+0x68/0x70 mm/kasan/report.c:435
 hci_conn_del+0x5c7/0x620 net/bluetooth/hci_conn.c:596
 hci_conn_hash_flush+0x189/0x220 net/bluetooth/hci_conn.c:1377
 hci_dev_do_close+0x542/0xc50 net/bluetooth/hci_core.c:1620
 hci_unregister_dev+0x170/0x7a0 net/bluetooth/hci_core.c:3191
 vhci_release+0x70/0xe0 drivers/bluetooth/hci_vhci.c:354
 __fput+0x25f/0x7a0 fs/file_table.c:210
 task_work_run+0x11f/0x190 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0xa08/0x27f0 kernel/exit.c:865
 do_group_exit+0x100/0x2e0 kernel/exit.c:962
 SYSC_exit_group kernel/exit.c:973 [inline]
 SyS_exit_group+0x19/0x20 kernel/exit.c:971
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45ce79
RSP: 002b:00007ffdb7728c88 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000045ce79
RDX: 00000000004168d1 RSI: 00000000016a85f0 RDI: 0000000000000043
RBP: 00000000004c2b1b R08: 000000000000000b R09: 0000000000000000
R10: 0000000001a6f940 R11: 0000000000000246 R12: 000000000000000f
R13: 00007ffdb7728dd0 R14: 000000000015856b R15: 00007ffdb7728de0

Allocated by task 8990:
 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]
 uevent_show+0x155/0x330 drivers/base/core.c:983
 dev_attr_show+0x4f/0xc0 drivers/base/core.c:707
 sysfs_kf_seq_show+0x1dd/0x420 fs/sysfs/file.c:63
 seq_read+0x4cf/0x1120 fs/seq_file.c:237
 kernfs_fop_read+0xd7/0x500 fs/kernfs/file.c:252
 __vfs_read+0xe4/0x620 fs/read_write.c:411
 vfs_read+0x139/0x340 fs/read_write.c:447
 SYSC_read fs/read_write.c:574 [inline]
 SyS_read+0xf2/0x210 fs/read_write.c:567
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

Freed by task 8990:
 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
 uevent_show+0x27e/0x330 drivers/base/core.c:996
 dev_attr_show+0x4f/0xc0 drivers/base/core.c:707
 sysfs_kf_seq_show+0x1dd/0x420 fs/sysfs/file.c:63
 seq_read+0x4cf/0x1120 fs/seq_file.c:237
 kernfs_fop_read+0xd7/0x500 fs/kernfs/file.c:252
 __vfs_read+0xe4/0x620 fs/read_write.c:411
 vfs_read+0x139/0x340 fs/read_write.c:447
 SYSC_read fs/read_write.c:574 [inline]
 SyS_read+0xf2/0x210 fs/read_write.c:567
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

The buggy address belongs to the object at ffff8880856e4ec0
 which belongs to the cache kmalloc-4096 of size 4096
The buggy address is located 2120 bytes inside of
 4096-byte region [ffff8880856e4ec0, ffff8880856e5ec0)
The buggy address belongs to the page:
page:ffffea000215b900 count:1 mapcount:0 mapping:ffff8880856e4ec0 index:0x0 compound_mapcount: 0
flags: 0xfffe0000008100(slab|head)
raw: 00fffe0000008100 ffff8880856e4ec0 0000000000000000 0000000100000001
raw: ffffea00020b1420 ffffea000223dd20 ffff88812fe52dc0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880856e5600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880856e5680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880856e5700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff8880856e5780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880856e5800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================