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+19a9f7...@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 syzk...@googlegroups.com.

syzbot will keep track of this bug report. See:
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[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+19a9f7...@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
==================================================================

[syzbot]

syzbot has bisected this bug to:

commit ff92b9dd9268507e23fc10cc4341626cef50367c
Author: Suganath Prabu <suganath-pra...@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+19a9f7...@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