KASAN: use-after-free Read in hci_cmd_timeout

KASAN: use-after-free Read in hci_cmd_timeout

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    83a50840 Merge tag 'seccomp-v5.1-rc8' of git://git.kernel...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14b99b60a00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ef1b87b455c397cf
dashboard link: https://syzkaller.appspot.com/bug?extid=19a9f729f05272857487
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+19a9f729f05272857487@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in hci_cmd_timeout+0x212/0x220  
net/bluetooth/hci_core.c:2617
Read of size 2 at addr ffff88809fa9ca08 by task kworker/1:1/22

CPU: 1 PID: 22 Comm: kworker/1:1 Not tainted 5.1.0-rc7+ #94
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: events hci_cmd_timeout
Call Trace:
  __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_load_n_noabort+0xf/0x20 mm/kasan/generic_report.c:142
  hci_cmd_timeout+0x212/0x220 net/bluetooth/hci_core.c:2617
  process_one_work+0x98e/0x1790 kernel/workqueue.c:2269
  worker_thread+0x98/0xe40 kernel/workqueue.c:2415
  kthread+0x357/0x430 kernel/kthread.c:253
  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

Allocated by task 8319:
  save_stack+0x45/0xd0 mm/kasan/common.c:75
  set_track mm/kasan/common.c:87 [inline]
  __kasan_kmalloc mm/kasan/common.c:497 [inline]
  __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:470
  kasan_kmalloc+0x9/0x10 mm/kasan/common.c:511
  __do_kmalloc_node mm/slab.c:3687 [inline]
  __kmalloc_node_track_caller+0x4e/0x70 mm/slab.c:3701
  __kmalloc_reserve.isra.0+0x40/0xf0 net/core/skbuff.c:140
  __alloc_skb+0x10b/0x5e0 net/core/skbuff.c:208
  alloc_skb include/linux/skbuff.h:1058 [inline]
  bt_skb_alloc include/net/bluetooth/bluetooth.h:339 [inline]
  hci_prepare_cmd+0x30/0x230 net/bluetooth/hci_request.c:287
  hci_req_add_ev+0xb0/0x210 net/bluetooth/hci_request.c:321
  __hci_cmd_sync_ev+0xfc/0x1c0 net/bluetooth/hci_request.c:133
  __hci_cmd_sync+0x37/0x50 net/bluetooth/hci_request.c:182
  btintel_enter_mfg+0x2e/0x90 drivers/bluetooth/btintel.c:82
  ag6xx_setup+0x106/0x820 drivers/bluetooth/hci_ag6xx.c:180
  hci_uart_setup+0x1c4/0x490 drivers/bluetooth/hci_ldisc.c:418
  hci_dev_do_open+0x78c/0x1780 net/bluetooth/hci_core.c:1450
  hci_power_on+0x10d/0x580 net/bluetooth/hci_core.c:2173
  process_one_work+0x98e/0x1790 kernel/workqueue.c:2269
  worker_thread+0x98/0xe40 kernel/workqueue.c:2415
  kthread+0x357/0x430 kernel/kthread.c:253
  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

Freed by task 8319:
  save_stack+0x45/0xd0 mm/kasan/common.c:75
  set_track mm/kasan/common.c:87 [inline]
  __kasan_slab_free+0x102/0x150 mm/kasan/common.c:459
  kasan_slab_free+0xe/0x10 mm/kasan/common.c:467
  __cache_free mm/slab.c:3499 [inline]
  kfree+0xcf/0x230 mm/slab.c:3822
  skb_free_head+0x93/0xb0 net/core/skbuff.c:557
  skb_release_data+0x576/0x7a0 net/core/skbuff.c:577
  skb_release_all+0x4d/0x60 net/core/skbuff.c:631
  __kfree_skb net/core/skbuff.c:645 [inline]
  kfree_skb net/core/skbuff.c:663 [inline]
  kfree_skb+0xe8/0x390 net/core/skbuff.c:657
  hci_dev_do_open+0xb2b/0x1780 net/bluetooth/hci_core.c:1552
  hci_power_on+0x10d/0x580 net/bluetooth/hci_core.c:2173
  process_one_work+0x98e/0x1790 kernel/workqueue.c:2269
  worker_thread+0x98/0xe40 kernel/workqueue.c:2415
  kthread+0x357/0x430 kernel/kthread.c:253
  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

The buggy address belongs to the object at ffff88809fa9ca00
  which belongs to the cache kmalloc-512 of size 512
The buggy address is located 8 bytes inside of
  512-byte region [ffff88809fa9ca00, ffff88809fa9cc00)
The buggy address belongs to the page:
page:ffffea00027ea700 count:1 mapcount:0 mapping:ffff8880aa400940 index:0x0
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea00023039c8 ffffea00026f9488 ffff8880aa400940
raw: 0000000000000000 ffff88809fa9c000 0000000100000006 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff88809fa9c900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff88809fa9c980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ffff88809fa9ca00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                       ^
  ffff88809fa9ca80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff88809fa9cb00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

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Re: KASAN: use-after-free Read in hci_cmd_timeout

[syzbot]

syzbot has found a reproducer for the following crash on:

HEAD commit:    eca94432 Bluetooth: Fix faulty expression for minimum encr..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1006cc8ba00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f6451f0da3d42d53
dashboard link: https://syzkaller.appspot.com/bug?extid=19a9f729f05272857487
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=125b7999a00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=176deefba00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+19a9f729f05272857487@syzkaller.appspotmail.com

Bluetooth: hci0: command 0xfc11 tx timeout
==================================================================
BUG: KASAN: use-after-free in hci_cmd_timeout+0x1fe/0x220  
net/bluetooth/hci_core.c:2614
Read of size 8 at addr ffff88809e8a3c48 by task kworker/0:5/9461

CPU: 0 PID: 9461 Comm: kworker/0:5 Not tainted 5.2.0-rc7+ #40
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: events hci_cmd_timeout
Call Trace:
  __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:188
  __kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
  kasan_report+0x12/0x20 mm/kasan/common.c:614
  __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
  hci_cmd_timeout+0x1fe/0x220 net/bluetooth/hci_core.c:2614
  process_one_work+0x989/0x1790 kernel/workqueue.c:2269
  worker_thread+0x98/0xe40 kernel/workqueue.c:2415
  kthread+0x354/0x420 kernel/kthread.c:255
  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Allocated by task 9446:
  save_stack+0x23/0x90 mm/kasan/common.c:71
  set_track mm/kasan/common.c:79 [inline]
  __kasan_kmalloc mm/kasan/common.c:489 [inline]
  __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462
  kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:497
  slab_post_alloc_hook mm/slab.h:437 [inline]
  slab_alloc mm/slab.c:3326 [inline]
  kmem_cache_alloc+0x11a/0x6f0 mm/slab.c:3488
  skb_clone+0x154/0x3d0 net/core/skbuff.c:1321
  hci_cmd_work+0xe0/0x2a0 net/bluetooth/hci_core.c:4495
  process_one_work+0x989/0x1790 kernel/workqueue.c:2269
  worker_thread+0x98/0xe40 kernel/workqueue.c:2415
  kthread+0x354/0x420 kernel/kthread.c:255
  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Freed by task 1501:
  save_stack+0x23/0x90 mm/kasan/common.c:71
  set_track mm/kasan/common.c:79 [inline]
  __kasan_slab_free+0x102/0x150 mm/kasan/common.c:451
  kasan_slab_free+0xe/0x10 mm/kasan/common.c:459
  __cache_free mm/slab.c:3432 [inline]
  kmem_cache_free+0x86/0x260 mm/slab.c:3698
  kfree_skbmem net/core/skbuff.c:620 [inline]
  kfree_skbmem+0xc5/0x150 net/core/skbuff.c:614
  __kfree_skb net/core/skbuff.c:677 [inline]
  kfree_skb net/core/skbuff.c:694 [inline]
  kfree_skb+0xf0/0x390 net/core/skbuff.c:688
  hci_dev_do_open+0xb20/0x1760 net/bluetooth/hci_core.c:1550
  hci_power_on+0x10d/0x580 net/bluetooth/hci_core.c:2171
  process_one_work+0x989/0x1790 kernel/workqueue.c:2269
  worker_thread+0x98/0xe40 kernel/workqueue.c:2415
  kthread+0x354/0x420 kernel/kthread.c:255
  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

The buggy address belongs to the object at ffff88809e8a3b80
  which belongs to the cache skbuff_head_cache of size 224
The buggy address is located 200 bytes inside of
  224-byte region [ffff88809e8a3b80, ffff88809e8a3c60)
The buggy address belongs to the page:
page:ffffea00027a28c0 refcount:1 mapcount:0 mapping:ffff88821baabb40  
index:0x0
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea00027b2d08 ffffea00021b83c8 ffff88821baabb40
raw: 0000000000000000 ffff88809e8a3040 000000010000000c 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff88809e8a3b00: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc
  ffff88809e8a3b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff88809e8a3c00: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
                                               ^
  ffff88809e8a3c80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
  ffff88809e8a3d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Re: KASAN: use-after-free Read in hci_cmd_timeout

[syzbot]

syzbot has bisected this bug to:

commit ff92b9dd9268507e23fc10cc4341626cef50367c
Author: Suganath Prabu <suganath-prabu.subramani@broadcom.com>
Date:   Thu Oct 25 14:03:40 2018 +0000

     scsi: mpt3sas: Update MPI headers to support Aero controllers

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=130ac8dda00000
start commit:   eca94432 Bluetooth: Fix faulty expression for minimum encr..
git tree:       upstream
final crash:    https://syzkaller.appspot.com/x/report.txt?x=108ac8dda00000
console output: https://syzkaller.appspot.com/x/log.txt?x=170ac8dda00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f6451f0da3d42d53
dashboard link: https://syzkaller.appspot.com/bug?extid=19a9f729f05272857487
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=125b7999a00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=176deefba00000

Reported-by: syzbot+19a9f729f05272857487@syzkaller.appspotmail.com
Fixes: ff92b9dd9268 ("scsi: mpt3sas: Update MPI headers to support Aero  
controllers")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

KASAN: use-after-free Read in hci_cmd_timeout

[Hao Sun]

Hello,

When using Healer to fuzz the latest Linux kernel, the following crash
was triggered.

HEAD commit: 42d43c92fc57  Merge branch 'for-linus'
git tree: upstream
console output:
https://drive.google.com/file/d/1ibZB4dfXnXoDznHOKdxaNC3OOq-mob9e/view?usp=sharing
kernel config: https://drive.google.com/file/d/1ibZB4dfXnXoDznHOKdxaNC3OOq-mob9e/view?usp=sharing

Sorry, I don't have a reproducer for this crash, hope the symbolized
report can help.
If you fix this issue, please add the following tag to the commit:
Reported-by: Hao Sun <sunhao.th@gmail.com>

==================================================================
BUG: KASAN: use-after-free in hci_cmd_timeout+0x203/0x210
net/bluetooth/hci_core.c:2774
Read of size 2 at addr ffff88801dcf8008 by task kworker/1:0/22

CPU: 1 PID: 22 Comm: kworker/1:0 Not tainted 5.15.0-rc3+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.13.0-1ubuntu1.1 04/01/2014
Workqueue: events hci_cmd_timeout
Call Trace:
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 print_address_description.constprop.0.cold+0x93/0x334 mm/kasan/report.c:256
 __kasan_report mm/kasan/report.c:442 [inline]
 kasan_report.cold+0x83/0xdf mm/kasan/report.c:459
 hci_cmd_timeout+0x203/0x210 net/bluetooth/hci_core.c:2774
 process_one_work+0x9df/0x16d0 kernel/workqueue.c:2297
 worker_thread+0x90/0xed0 kernel/workqueue.c:2444
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Allocated by task 14281:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 ____kasan_kmalloc mm/kasan/common.c:513 [inline]
 ____kasan_kmalloc mm/kasan/common.c:472 [inline]
 __kasan_kmalloc+0xa4/0xd0 mm/kasan/common.c:522
 kasan_kmalloc ./include/linux/kasan.h:264 [inline]
 __kmalloc+0x1c1/0x390 mm/slub.c:4391
 kmalloc ./include/linux/slab.h:596 [inline]
 kzalloc ./include/linux/slab.h:721 [inline]
 ops_init+0xfb/0x420 net/core/net_namespace.c:130
 setup_net+0x415/0xa40 net/core/net_namespace.c:326
 copy_net_ns+0x2d9/0x660 net/core/net_namespace.c:470
 create_new_namespaces.isra.0+0x3cb/0xae0 kernel/nsproxy.c:110
 copy_namespaces+0x391/0x450 kernel/nsproxy.c:178
 copy_process+0x2d37/0x73d0 kernel/fork.c:2197
 kernel_clone+0xe7/0x10d0 kernel/fork.c:2584
 __do_sys_clone+0xc8/0x110 kernel/fork.c:2701
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 6594:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:46
 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:360
 ____kasan_slab_free mm/kasan/common.c:366 [inline]
 ____kasan_slab_free mm/kasan/common.c:328 [inline]
 __kasan_slab_free+0x100/0x140 mm/kasan/common.c:374
 kasan_slab_free ./include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1700 [inline]
 slab_free_freelist_hook mm/slub.c:1725 [inline]
 slab_free mm/slub.c:3483 [inline]
 kfree+0xfc/0x700 mm/slub.c:4543
 skb_free_head+0x8b/0xa0 net/core/skbuff.c:654
 skb_release_data+0x5bf/0x700 net/core/skbuff.c:676
 skb_release_all+0x46/0x60 net/core/skbuff.c:741
 __kfree_skb net/core/skbuff.c:755 [inline]
 kfree_skb net/core/skbuff.c:773 [inline]
 kfree_skb+0xfa/0x3a0 net/core/skbuff.c:767
 hci_dev_do_open+0xa50/0x1820 net/bluetooth/hci_core.c:1634
 hci_power_on+0x133/0x650 net/bluetooth/hci_core.c:2263
 process_one_work+0x9df/0x16d0 kernel/workqueue.c:2297
 worker_thread+0x90/0xed0 kernel/workqueue.c:2444
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Last potentially related work creation:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_record_aux_stack+0xe9/0x110 mm/kasan/generic.c:348
 kvfree_call_rcu+0x74/0xab0 kernel/rcu/tree.c:3552
 drop_sysctl_table+0x2e7/0x3b0 fs/proc/proc_sysctl.c:1647
 unregister_sysctl_table+0xc2/0x190 fs/proc/proc_sysctl.c:1685
 mpls_dev_sysctl_unregister+0x80/0xc0 net/mpls/af_mpls.c:1441
 mpls_dev_notify+0x458/0x770 net/mpls/af_mpls.c:1621
 notifier_call_chain+0xb5/0x200 kernel/notifier.c:83
 call_netdevice_notifiers_info net/core/dev.c:1996 [inline]
 call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:1981
 call_netdevice_notifiers_extack net/core/dev.c:2008 [inline]
 call_netdevice_notifiers net/core/dev.c:2022 [inline]
 unregister_netdevice_many+0x930/0x14e0 net/core/dev.c:11043
 vti6_exit_batch_net+0x3ad/0x690 net/ipv6/ip6_vti.c:1188
 ops_exit_list.isra.0+0x103/0x150 net/core/net_namespace.c:171
 cleanup_net+0x511/0xa90 net/core/net_namespace.c:591
 process_one_work+0x9df/0x16d0 kernel/workqueue.c:2297
 worker_thread+0x90/0xed0 kernel/workqueue.c:2444
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Second to last potentially related work creation:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_record_aux_stack+0xe9/0x110 mm/kasan/generic.c:348
 kvfree_call_rcu+0x74/0xab0 kernel/rcu/tree.c:3552
 ma_put net/ipv6/mcast.c:869 [inline]
 ma_put+0x11c/0x180 net/ipv6/mcast.c:865
 __ipv6_dev_mc_dec+0x278/0x340 net/ipv6/mcast.c:982
 addrconf_leave_solict.part.0+0xb5/0xf0 net/ipv6/addrconf.c:2189
 addrconf_leave_solict net/ipv6/addrconf.c:6124 [inline]
 __ipv6_ifa_notify+0x2a7/0xb40 net/ipv6/addrconf.c:6124
 addrconf_ifdown+0x92f/0x14d0 net/ipv6/addrconf.c:3835
 addrconf_notify+0xeb/0x1bc0 net/ipv6/addrconf.c:3646
 notifier_call_chain+0xb5/0x200 kernel/notifier.c:83
 call_netdevice_notifiers_info net/core/dev.c:1996 [inline]
 call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:1981
 call_netdevice_notifiers_extack net/core/dev.c:2008 [inline]
 call_netdevice_notifiers net/core/dev.c:2022 [inline]
 dev_close_many+0x2fc/0x630 net/core/dev.c:1597
 unregister_netdevice_many+0x420/0x14e0 net/core/dev.c:11020
 default_device_exit_batch+0x302/0x3c0 net/core/dev.c:11573
 ops_exit_list.isra.0+0x103/0x150 net/core/net_namespace.c:171
 cleanup_net+0x511/0xa90 net/core/net_namespace.c:591
 process_one_work+0x9df/0x16d0 kernel/workqueue.c:2297
 worker_thread+0x90/0xed0 kernel/workqueue.c:2444
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

The buggy address belongs to the object at ffff88801dcf8000
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 8 bytes inside of
 512-byte region [ffff88801dcf8000, ffff88801dcf8200)
The buggy address belongs to the page:
page:ffffea0000773e00 refcount:1 mapcount:0 mapping:0000000000000000
index:0x0 pfn:0x1dcf8
head:ffffea0000773e00 order:2 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 0000000000000000 0000000300000001 ffff888010c42c80
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask
0xd2000(__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid
1, ts 19546740260, free_ts 0
 set_page_owner ./include/linux/page_owner.h:31 [inline]
 post_alloc_hook mm/page_alloc.c:2418 [inline]
 prep_new_page+0x1a5/0x240 mm/page_alloc.c:2424
 get_page_from_freelist+0x1f10/0x3b70 mm/page_alloc.c:4153
 __alloc_pages+0x306/0x6e0 mm/page_alloc.c:5375
 alloc_page_interleave+0x1e/0x1f0 mm/mempolicy.c:2042
 alloc_pages+0x1e4/0x240 mm/mempolicy.c:2192
 alloc_slab_page mm/slub.c:1763 [inline]
 allocate_slab mm/slub.c:1900 [inline]
 new_slab+0x34a/0x480 mm/slub.c:1963
 ___slab_alloc+0xa9f/0x10d0 mm/slub.c:2994
 __slab_alloc.isra.0+0x4d/0xa0 mm/slub.c:3081
 slab_alloc_node mm/slub.c:3172 [inline]
 slab_alloc mm/slub.c:3214 [inline]
 kmem_cache_alloc_trace+0x31c/0x340 mm/slub.c:3231
 kmalloc ./include/linux/slab.h:591 [inline]
 usb_cache_string+0x5e/0x110 drivers/usb/core/message.c:1027
 usb_enumerate_device drivers/usb/core/hub.c:2405 [inline]
 usb_new_device+0x15b/0x760 drivers/usb/core/hub.c:2533
 register_root_hub+0x420/0x572 drivers/usb/core/hcd.c:1010
 usb_add_hcd.cold+0x1100/0x134a drivers/usb/core/hcd.c:2972
 vhci_hcd_probe+0x150/0x3a0 drivers/usb/usbip/vhci_hcd.c:1362
 platform_probe+0xfc/0x1f0 drivers/base/platform.c:1411
 call_driver_probe drivers/base/dd.c:517 [inline]
 really_probe drivers/base/dd.c:596 [inline]
 really_probe+0x245/0xbd0 drivers/base/dd.c:541
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88801dcf7f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88801dcf7f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88801dcf8000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff88801dcf8080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88801dcf8100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================