KASAN: use-after-free Read in klist_dec_and_del

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 6ca2f514c578 Linux 4.19.201
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=146cdf7a300000
kernel config: https://syzkaller.appspot.com/x/.config?x=e245acf152ace855
dashboard link: https://syzkaller.appspot.com/bug?extid=675cee2a9f10b1ecf7c4
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+675cee...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in __list_del_entry_valid+0xe0/0xf0 lib/list_debug.c:51
Read of size 8 at addr ffff8880b0b31320 by task kworker/u5:0/1717

CPU: 1 PID: 1717 Comm: kworker/u5:0 Not tainted 4.19.201-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: hci5 hci_rx_work
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1fc/0x2ef lib/dump_stack.c:118
print_address_description.cold+0x54/0x219 mm/kasan/report.c:256
kasan_report_error.cold+0x8a/0x1b9 mm/kasan/report.c:354
kasan_report mm/kasan/report.c:412 [inline]
__asan_report_load8_noabort+0x88/0x90 mm/kasan/report.c:433
__list_del_entry_valid+0xe0/0xf0 lib/list_debug.c:51
__list_del_entry include/linux/list.h:117 [inline]
list_del include/linux/list.h:125 [inline]
klist_release lib/klist.c:190 [inline]
kref_put include/linux/kref.h:70 [inline]
klist_dec_and_del+0x97/0x480 lib/klist.c:207
klist_put+0x7a/0x150 lib/klist.c:218
device_del+0x162/0xaf0 drivers/base/core.c:2320
hci_conn_del_sysfs+0xdc/0x180 net/bluetooth/hci_sysfs.c:78
hci_conn_cleanup+0x24b/0x550 net/bluetooth/hci_conn.c:128
hci_conn_del+0x2a0/0x780 net/bluetooth/hci_conn.c:611
hci_disconn_complete_evt net/bluetooth/hci_event.c:2678 [inline]
hci_event_packet+0x11ca/0x7e20 net/bluetooth/hci_event.c:5787
hci_rx_work+0x4ad/0xc70 net/bluetooth/hci_core.c:4366
process_one_work+0x864/0x1570 kernel/workqueue.c:2153
worker_thread+0x64c/0x1130 kernel/workqueue.c:2296
kthread+0x33f/0x460 kernel/kthread.c:259
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

Allocated by task 1717:
kmem_cache_alloc_trace+0x12f/0x380 mm/slab.c:3625
kmalloc include/linux/slab.h:515 [inline]
kzalloc include/linux/slab.h:709 [inline]
device_private_init drivers/base/core.c:2035 [inline]
device_add+0xe5a/0x16d0 drivers/base/core.c:2080
hci_conn_add_sysfs+0x97/0x1a0 net/bluetooth/hci_sysfs.c:53
hci_conn_complete_evt net/bluetooth/hci_event.c:2445 [inline]
hci_event_packet+0x2647/0x7e20 net/bluetooth/hci_event.c:5779
hci_rx_work+0x4ad/0xc70 net/bluetooth/hci_core.c:4366
process_one_work+0x864/0x1570 kernel/workqueue.c:2153
worker_thread+0x64c/0x1130 kernel/workqueue.c:2296
kthread+0x33f/0x460 kernel/kthread.c:259
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

Freed by task 8154:
__cache_free mm/slab.c:3503 [inline]
kfree+0xcc/0x210 mm/slab.c:3822
device_add+0x713/0x16d0 drivers/base/core.c:2213
hci_conn_add_sysfs+0x97/0x1a0 net/bluetooth/hci_sysfs.c:53
hci_sync_conn_complete_evt.isra.0+0x9e9/0xca0 net/bluetooth/hci_event.c:4091
hci_event_packet+0x391f/0x7e20 net/bluetooth/hci_event.c:5869
hci_rx_work+0x4ad/0xc70 net/bluetooth/hci_core.c:4366
process_one_work+0x864/0x1570 kernel/workqueue.c:2153
worker_thread+0x64c/0x1130 kernel/workqueue.c:2296
kthread+0x33f/0x460 kernel/kthread.c:259
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

The buggy address belongs to the object at ffff8880b0b312c0
which belongs to the cache kmalloc-256 of size 256
The buggy address is located 96 bytes inside of
256-byte region [ffff8880b0b312c0, ffff8880b0b313c0)
The buggy address belongs to the page:
page:ffffea0002c2cc40 count:1 mapcount:0 mapping:ffff88813bff07c0 index:0xffff8880b0b317c0
flags: 0xfff00000000100(slab)
raw: 00fff00000000100 ffffea0002a52608 ffffea0002720248 ffff88813bff07c0
raw: ffff8880b0b317c0 ffff8880b0b31040 000000010000000b 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8880b0b31200: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc
ffff8880b0b31280: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff8880b0b31300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8880b0b31380: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff8880b0b31400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 6ca2f514c578 Linux 4.19.201
git tree: linux-4.19.y

console output: https://syzkaller.appspot.com/x/log.txt?x=16315fc6300000

kernel config: https://syzkaller.appspot.com/x/.config?x=e245acf152ace855
dashboard link: https://syzkaller.appspot.com/bug?extid=675cee2a9f10b1ecf7c4
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15335e21300000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1247e09a300000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+675cee...@syzkaller.appspotmail.com

kthread+0x33f/0x460 kernel/kthread.c:259
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

kobject_add_internal failed for hci0:200 with -EEXIST, don't try to register things with the same name in the same directory.
Bluetooth: hci0: failed to register connection device

==================================================================
BUG: KASAN: use-after-free in __list_del_entry_valid+0xe0/0xf0 lib/list_debug.c:51

Read of size 8 at addr ffff8880a449fb20 by task kworker/u5:1/8123

CPU: 1 PID: 8123 Comm: kworker/u5:1 Not tainted 4.19.201-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011

Workqueue: hci0 hci_rx_work

Allocated by task 8123:

kmem_cache_alloc_trace+0x12f/0x380 mm/slab.c:3625
kmalloc include/linux/slab.h:515 [inline]
kzalloc include/linux/slab.h:709 [inline]
device_private_init drivers/base/core.c:2035 [inline]
device_add+0xe5a/0x16d0 drivers/base/core.c:2080
hci_conn_add_sysfs+0x97/0x1a0 net/bluetooth/hci_sysfs.c:53
hci_conn_complete_evt net/bluetooth/hci_event.c:2445 [inline]
hci_event_packet+0x2647/0x7e20 net/bluetooth/hci_event.c:5779
hci_rx_work+0x4ad/0xc70 net/bluetooth/hci_core.c:4366
process_one_work+0x864/0x1570 kernel/workqueue.c:2153
worker_thread+0x64c/0x1130 kernel/workqueue.c:2296
kthread+0x33f/0x460 kernel/kthread.c:259
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

Freed by task 8123:

__cache_free mm/slab.c:3503 [inline]
kfree+0xcc/0x210 mm/slab.c:3822
device_add+0x713/0x16d0 drivers/base/core.c:2213
hci_conn_add_sysfs+0x97/0x1a0 net/bluetooth/hci_sysfs.c:53
hci_sync_conn_complete_evt.isra.0+0x9e9/0xca0 net/bluetooth/hci_event.c:4091
hci_event_packet+0x391f/0x7e20 net/bluetooth/hci_event.c:5869
hci_rx_work+0x4ad/0xc70 net/bluetooth/hci_core.c:4366
process_one_work+0x864/0x1570 kernel/workqueue.c:2153
worker_thread+0x64c/0x1130 kernel/workqueue.c:2296
kthread+0x33f/0x460 kernel/kthread.c:259
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

The buggy address belongs to the object at ffff8880a449fac0

which belongs to the cache kmalloc-256 of size 256
The buggy address is located 96 bytes inside of

256-byte region [ffff8880a449fac0, ffff8880a449fbc0)

The buggy address belongs to the page:

page:ffffea00029127c0 count:1 mapcount:0 mapping:ffff88813bff07c0 index:0xffff8880a449f200
flags: 0xfff00000000100(slab)
raw: 00fff00000000100 ffffea0002d488c8 ffffea0002917c48 ffff88813bff07c0
raw: ffff8880a449f200 ffff8880a449f0c0 0000000100000007 0000000000000000

page dumped because: kasan: bad access detected

Memory state around the buggy address:

ffff8880a449fa00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880a449fa80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff8880a449fb00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8880a449fb80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff8880a449fc00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================