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@xxxxxxxxxxxxxxxxxxxxxxxxx
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
==================================================================
