KASAN: use-after-free Read in hci_cmd

KASAN: use-after-free Read in hci_cmd_timeout
Status: upstream: reported C repro on 2019/09/06 20:31
Reported-by: syzbot+188c65dac35116b39205@syzkaller.appspotmail.com
First crash: 273d, last: 2d20h

similar bugs (2):
Kernel	Title	Repro	Bisected	Count	Last	Reported	Patched	Status
linux-4.19	KASAN: use-after-free Read in hci_cmd_timeout	syz		3	9d20h	279d	0/1	upstream: reported syz repro on 2019/09/01 02:37
upstream	KASAN: use-after-free Read in hci_cmd_timeout	C	cause+fix	10	105d	396d	0/17	upstream: reported C repro on 2019/05/07 09:10

Sample crash report:

Bluetooth: hci5: Frame reassembly failed (-84)
Bluetooth: hci1: Entering manufacturer mode failed (-110)
Bluetooth: hci1 command 0xfc11 tx timeout
Bluetooth: hci2: Entering manufacturer mode failed (-110)
==================================================================
BUG: KASAN: use-after-free in hci_cmd_timeout+0x1aa/0x1c0 net/bluetooth/hci_core.c:2525
Read of size 2 at addr ffff88809ded8cc8 by task kworker/0:1/24

CPU: 0 PID: 24 Comm: kworker/0:1 Not tainted 4.14.158-syzkaller #0
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:17 [inline]
 dump_stack+0x142/0x197 lib/dump_stack.c:58
 print_address_description.cold+0x7c/0x1dc mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report mm/kasan/report.c:409 [inline]
 kasan_report.cold+0xa9/0x2af mm/kasan/report.c:393
 __asan_report_load_n_noabort+0xf/0x20 mm/kasan/report.c:440
 hci_cmd_timeout+0x1aa/0x1c0 net/bluetooth/hci_core.c:2525
 process_one_work+0x863/0x1600 kernel/workqueue.c:2114
 worker_thread+0x5d9/0x1050 kernel/workqueue.c:2248
 kthread+0x319/0x430 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Allocated by task 6991:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x45/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc mm/kasan/kasan.c:551 [inline]
 kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:529
 __do_kmalloc_node mm/slab.c:3682 [inline]
 __kmalloc_node_track_caller+0x51/0x80 mm/slab.c:3696
 __kmalloc_reserve.isra.0+0x40/0xe0 net/core/skbuff.c:137
 __alloc_skb+0xcf/0x500 net/core/skbuff.c:205
 alloc_skb include/linux/skbuff.h:980 [inline]
 bt_skb_alloc include/net/bluetooth/bluetooth.h:336 [inline]
 hci_prepare_cmd+0x30/0x220 net/bluetooth/hci_request.c:298
 hci_req_add_ev+0xa3/0x200 net/bluetooth/hci_request.c:332
 __hci_cmd_sync_ev+0x152/0x610 net/bluetooth/hci_request.c:129
 __hci_cmd_sync+0x37/0x50 net/bluetooth/hci_request.c:185
 btintel_enter_mfg+0x74/0xe0 drivers/bluetooth/btintel.c:81
 ag6xx_setup+0xfb/0x770 drivers/bluetooth/hci_ag6xx.c:180
 hci_uart_setup+0x1a3/0x430 drivers/bluetooth/hci_ldisc.c:429
 hci_dev_do_open+0x575/0xf80 net/bluetooth/hci_core.c:1384
 hci_power_on+0x8d/0x3d0 net/bluetooth/hci_core.c:2080
 process_one_work+0x863/0x1600 kernel/workqueue.c:2114
 worker_thread+0x5d9/0x1050 kernel/workqueue.c:2248
 kthread+0x319/0x430 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Freed by task 6991:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x45/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x75/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xcc/0x270 mm/slab.c:3815
 skb_free_head+0x8b/0xb0 net/core/skbuff.c:554
 skb_release_data+0x543/0x7c0 net/core/skbuff.c:574
 skb_release_all+0x4d/0x60 net/core/skbuff.c:631
 __kfree_skb net/core/skbuff.c:645 [inline]
 kfree_skb+0xb5/0x350 net/core/skbuff.c:663
 hci_dev_do_open+0x9db/0xf80 net/bluetooth/hci_core.c:1469
 hci_power_on+0x8d/0x3d0 net/bluetooth/hci_core.c:2080
 process_one_work+0x863/0x1600 kernel/workqueue.c:2114
 worker_thread+0x5d9/0x1050 kernel/workqueue.c:2248
 kthread+0x319/0x430 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

The buggy address belongs to the object at ffff88809ded8cc0
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 8 bytes inside of
 512-byte region [ffff88809ded8cc0, ffff88809ded8ec0)
The buggy address belongs to the page:
page:ffffea000277b600 count:1 mapcount:0 mapping:ffff88809ded8040 index:0x0
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffff88809ded8040 0000000000000000 0000000100000006
raw: ffffea00026c61e0 ffffea00026d1420 ffff8880aa800940 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809ded8b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809ded8c00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff88809ded8c80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
                                              ^
 ffff88809ded8d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809ded8d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Fix bisection attempts:
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro
ci2-linux-4-14	2020/06/03 18:15	linux-4.14.y	c6db52a8	85f26751	.config	log	report	syz	C
ci2-linux-4-14	2020/05/04 17:38	linux-4.14.y	773e2b1c	85f26751	.config	log	report	syz	C
ci2-linux-4-14	2020/04/04 16:57	linux-4.14.y	4520f06b	85f26751	.config	log	report	syz	C
ci2-linux-4-14	2020/02/24 06:34	linux-4.14.y	98db2bf2	85f26751	.config	log	report	syz	C
ci2-linux-4-14	2020/01/05 22:13	linux-4.14.y	84f5ad46	85f26751	.config	log	report	syz	C

Crashes (6):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	Maintainers
ci2-linux-4-14	2019/12/06 21:33	linux-4.14.y	a844dc4c	85f26751	.config	log	report	syz	C	davem@davemloft.net, gustavo@padovan.org, johan.hedberg@gmail.com, linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org, marcel@holtmann.org, netdev@vger.kernel.org
ci2-linux-4-14	2019/09/06 19:30	linux-4.14.y	414510bc	acb5b744	.config	log	report	syz		davem@davemloft.net, gustavo@padovan.org, johan.hedberg@gmail.com, linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org, marcel@holtmann.org, netdev@vger.kernel.org
ci2-linux-4-14	2020/03/05 16:19	linux-4.14.y	78d697fc	b655d91b	.config	log	report			davem@davemloft.net, gustavo@padovan.org, johan.hedberg@gmail.com, linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org, marcel@holtmann.org, netdev@vger.kernel.org
ci2-linux-4-14	2020/01/25 05:53	linux-4.14.y	8bac5040	2e95ab33	.config	log	report			davem@davemloft.net, gustavo@padovan.org, johan.hedberg@gmail.com, linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org, marcel@holtmann.org, netdev@vger.kernel.org
ci2-linux-4-14	2019/12/06 20:17	linux-4.14.y	a844dc4c	85f26751	.config	log	report			davem@davemloft.net, gustavo@padovan.org, johan.hedberg@gmail.com, linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org, marcel@holtmann.org, netdev@vger.kernel.org
ci2-linux-4-14	2019/11/24 12:33	linux-4.14.y	43598c57	598ca6c8	.config	log	report			davem@davemloft.net, gustavo@padovan.org, johan.hedberg@gmail.com, linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org, marcel@holtmann.org, netdev@vger.kernel.org