KASAN: use-after-free Read in put_device

From: syzbot
Date: Sat May 23 2020 - 13:04:40 EST

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Hello,

syzbot found the following crash on:

HEAD commit: c11d28ab Add linux-next specific files for 20200522
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=114e4f06100000
kernel config: https://syzkaller.appspot.com/x/.config?x=3f6dbdea4159fb66
dashboard link: https://syzkaller.appspot.com/bug?extid=60f9ee7f99afe29ef9fa
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10ba16e2100000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16caefe6100000

The bug was bisected to:

commit 4ef12f7198023c09ad6d25b652bd8748c965c7fa
Author: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
Date: Wed May 13 15:18:40 2020 +0000

kobject: Make sure the parent does not get released before its children

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=140a5cba100000
final crash: https://syzkaller.appspot.com/x/report.txt?x=160a5cba100000
console output: https://syzkaller.appspot.com/x/log.txt?x=120a5cba100000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+60f9ee7f99afe29ef9fa@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 4ef12f719802 ("kobject: Make sure the parent does not get released before its children")

i2c-tiny-usb 1-1:0.0: version 63.ce found at bus 001 address 002
(null): failure reading functionality
i2c i2c-0: failure reading functionality
i2c i2c-0: connected i2c-tiny-usb device
usb 1-1: USB disconnect, device number 2
==================================================================
BUG: KASAN: use-after-free in kobject_put+0x296/0x2f0 lib/kobject.c:745
Read of size 1 at addr ffff8880a8ce3054 by task kworker/0:7/2516

CPU: 0 PID: 2516 Comm: kworker/0:7 Not tainted 5.7.0-rc6-next-20200522-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: usb_hub_wq hub_event
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x18f/0x20d lib/dump_stack.c:118
print_address_description.constprop.0.cold+0xd3/0x413 mm/kasan/report.c:383
__kasan_report mm/kasan/report.c:513 [inline]
kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
kobject_put+0x296/0x2f0 lib/kobject.c:745
put_device+0x1b/0x30 drivers/base/core.c:2761
i2cdev_detach_adapter.part.0+0x53/0x70 drivers/i2c/i2c-dev.c:689
i2cdev_detach_adapter drivers/i2c/i2c-dev.c:647 [inline]
i2cdev_notifier_call+0xad/0xc0 drivers/i2c/i2c-dev.c:704
notifier_call_chain+0xc0/0x230 kernel/notifier.c:83
__blocking_notifier_call_chain kernel/notifier.c:284 [inline]
__blocking_notifier_call_chain kernel/notifier.c:271 [inline]
blocking_notifier_call_chain kernel/notifier.c:295 [inline]
blocking_notifier_call_chain+0x85/0xa0 kernel/notifier.c:292
device_del+0x17e/0xd30 drivers/base/core.c:2813
device_unregister+0x11/0x30 drivers/base/core.c:2871
i2c_del_adapter drivers/i2c/i2c-core-base.c:1671 [inline]
i2c_del_adapter+0x42b/0x590 drivers/i2c/i2c-core-base.c:1610
i2c_tiny_usb_disconnect+0x3a/0xb0 drivers/i2c/busses/i2c-tiny-usb.c:283
usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:436
__device_release_driver drivers/base/dd.c:1113 [inline]
device_release_driver_internal+0x432/0x500 drivers/base/dd.c:1144
bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:533
device_del+0x481/0xd30 drivers/base/core.c:2839
usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1245
usb_disconnect+0x284/0x8d0 drivers/usb/core/hub.c:2217
hub_port_connect drivers/usb/core/hub.c:5059 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5348 [inline]
port_event drivers/usb/core/hub.c:5494 [inline]
hub_event+0x17ca/0x38f0 drivers/usb/core/hub.c:5576
process_one_work+0x965/0x16a0 kernel/workqueue.c:2268
process_scheduled_works kernel/workqueue.c:2330 [inline]
worker_thread+0x7ab/0xe20 kernel/workqueue.c:2416
kthread+0x3b5/0x4a0 kernel/kthread.c:291
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351

Allocated by task 2516:
save_stack+0x1b/0x40 mm/kasan/common.c:48
set_track mm/kasan/common.c:56 [inline]
__kasan_kmalloc mm/kasan/common.c:494 [inline]
__kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:467
kmem_cache_alloc_trace+0x153/0x7d0 mm/slab.c:3551
kmalloc include/linux/slab.h:555 [inline]
kzalloc include/linux/slab.h:669 [inline]
get_free_i2c_dev drivers/i2c/i2c-dev.c:76 [inline]
i2cdev_attach_adapter.part.0+0x9a/0x3f0 drivers/i2c/i2c-dev.c:651
i2cdev_attach_adapter drivers/i2c/i2c-dev.c:647 [inline]
i2cdev_notifier_call drivers/i2c/i2c-dev.c:702 [inline]
i2cdev_notifier_call+0x9b/0xc0 drivers/i2c/i2c-dev.c:695
notifier_call_chain+0xc0/0x230 kernel/notifier.c:83
__blocking_notifier_call_chain kernel/notifier.c:284 [inline]
__blocking_notifier_call_chain kernel/notifier.c:271 [inline]
blocking_notifier_call_chain kernel/notifier.c:295 [inline]
blocking_notifier_call_chain+0x85/0xa0 kernel/notifier.c:292
device_add+0xa6e/0x1900 drivers/base/core.c:2640
i2c_register_adapter+0x30d/0xb00 drivers/i2c/i2c-core-base.c:1415
i2c_add_adapter+0xba/0x100 drivers/i2c/i2c-core-base.c:1528
i2c_tiny_usb_probe+0x3a8/0x528 drivers/i2c/busses/i2c-tiny-usb.c:265
usb_probe_interface+0x305/0x7a0 drivers/usb/core/driver.c:374
really_probe+0x281/0x6d0 drivers/base/dd.c:525
driver_probe_device+0xfe/0x1d0 drivers/base/dd.c:701
__device_attach_driver+0x1c2/0x220 drivers/base/dd.c:807
bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:431
__device_attach+0x21a/0x360 drivers/base/dd.c:873
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:491
device_add+0xaf1/0x1900 drivers/base/core.c:2662
usb_set_configuration+0xec5/0x1740 drivers/usb/core/message.c:2032
usb_generic_driver_probe+0x9d/0xe0 drivers/usb/core/generic.c:241
usb_probe_device+0xc6/0x1f0 drivers/usb/core/driver.c:272
really_probe+0x281/0x6d0 drivers/base/dd.c:525
driver_probe_device+0xfe/0x1d0 drivers/base/dd.c:701
__device_attach_driver+0x1c2/0x220 drivers/base/dd.c:807
bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:431
__device_attach+0x21a/0x360 drivers/base/dd.c:873
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:491
device_add+0xaf1/0x1900 drivers/base/core.c:2662
usb_new_device.cold+0x753/0x103d drivers/usb/core/hub.c:2554
hub_port_connect drivers/usb/core/hub.c:5208 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5348 [inline]
port_event drivers/usb/core/hub.c:5494 [inline]
hub_event+0x1eca/0x38f0 drivers/usb/core/hub.c:5576
process_one_work+0x965/0x16a0 kernel/workqueue.c:2268
worker_thread+0x96/0xe20 kernel/workqueue.c:2414
kthread+0x3b5/0x4a0 kernel/kthread.c:291
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351

Freed by task 2516:
save_stack+0x1b/0x40 mm/kasan/common.c:48
set_track mm/kasan/common.c:56 [inline]
kasan_set_free_info mm/kasan/common.c:316 [inline]
__kasan_slab_free+0xf7/0x140 mm/kasan/common.c:455
__cache_free mm/slab.c:3426 [inline]
kfree+0x109/0x2b0 mm/slab.c:3757
device_release+0x71/0x200 drivers/base/core.c:1541
kobject_cleanup lib/kobject.c:701 [inline]
kobject_release lib/kobject.c:732 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x1c8/0x2f0 lib/kobject.c:749
cdev_device_del+0x69/0x80 fs/char_dev.c:575
put_i2c_dev+0x160/0x1b0 drivers/i2c/i2c-dev.c:93
i2cdev_detach_adapter.part.0+0x53/0x70 drivers/i2c/i2c-dev.c:689
i2cdev_detach_adapter drivers/i2c/i2c-dev.c:647 [inline]
i2cdev_notifier_call+0xad/0xc0 drivers/i2c/i2c-dev.c:704
notifier_call_chain+0xc0/0x230 kernel/notifier.c:83
__blocking_notifier_call_chain kernel/notifier.c:284 [inline]
__blocking_notifier_call_chain kernel/notifier.c:271 [inline]
blocking_notifier_call_chain kernel/notifier.c:295 [inline]
blocking_notifier_call_chain+0x85/0xa0 kernel/notifier.c:292
device_del+0x17e/0xd30 drivers/base/core.c:2813
device_unregister+0x11/0x30 drivers/base/core.c:2871
i2c_del_adapter drivers/i2c/i2c-core-base.c:1671 [inline]
i2c_del_adapter+0x42b/0x590 drivers/i2c/i2c-core-base.c:1610
i2c_tiny_usb_disconnect+0x3a/0xb0 drivers/i2c/busses/i2c-tiny-usb.c:283
usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:436
__device_release_driver drivers/base/dd.c:1113 [inline]
device_release_driver_internal+0x432/0x500 drivers/base/dd.c:1144
bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:533
device_del+0x481/0xd30 drivers/base/core.c:2839
usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1245
usb_disconnect+0x284/0x8d0 drivers/usb/core/hub.c:2217
hub_port_connect drivers/usb/core/hub.c:5059 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5348 [inline]
port_event drivers/usb/core/hub.c:5494 [inline]
hub_event+0x17ca/0x38f0 drivers/usb/core/hub.c:5576
process_one_work+0x965/0x16a0 kernel/workqueue.c:2268
process_scheduled_works kernel/workqueue.c:2330 [inline]
worker_thread+0x7ab/0xe20 kernel/workqueue.c:2416
kthread+0x3b5/0x4a0 kernel/kthread.c:291
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351

The buggy address belongs to the object at ffff8880a8ce3000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 84 bytes inside of
2048-byte region [ffff8880a8ce3000, ffff8880a8ce3800)
The buggy address belongs to the page:
page:ffffea0002a338c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea000240c988 ffffea00027fd2c8 ffff8880aa000e00
raw: 0000000000000000 ffff8880a8ce3000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8880a8ce2f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc
ffff8880a8ce2f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880a8ce3000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8880a8ce3080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880a8ce3100: 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@xxxxxxxxxxxxxxxxx

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

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