[PATCH v2] Bluetooth: fix use-after-free in device_for_each_child()

[PATCH v2] Bluetooth: fix use-after-free in device_for_each_child()

[Dmitry Antipov]

Syzbot has reported the following KASAN splat:

BUG: KASAN: slab-use-after-free in device_for_each_child+0x18f/0x1a0
Read of size 8 at addr ffff88801f605308 by task kbnepd bnep0/4980

CPU: 0 UID: 0 PID: 4980 Comm: kbnepd bnep0 Not tainted 6.12.0-rc4-00161-gae90f6a6170d #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-2.fc40 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x100/0x190
 ? device_for_each_child+0x18f/0x1a0
 print_report+0x13a/0x4cb
 ? __virt_addr_valid+0x5e/0x590
 ? __phys_addr+0xc6/0x150
 ? device_for_each_child+0x18f/0x1a0
 kasan_report+0xda/0x110
 ? device_for_each_child+0x18f/0x1a0
 ? __pfx_dev_memalloc_noio+0x10/0x10
 device_for_each_child+0x18f/0x1a0
 ? __pfx_device_for_each_child+0x10/0x10
 pm_runtime_set_memalloc_noio+0xf2/0x180
 netdev_unregister_kobject+0x1ed/0x270
 unregister_netdevice_many_notify+0x123c/0x1d80
 ? __mutex_trylock_common+0xde/0x250
 ? __pfx_unregister_netdevice_many_notify+0x10/0x10
 ? trace_contention_end+0xe6/0x140
 ? __mutex_lock+0x4e7/0x8f0
 ? __pfx_lock_acquire.part.0+0x10/0x10
 ? rcu_is_watching+0x12/0xc0
 ? unregister_netdev+0x12/0x30
 unregister_netdevice_queue+0x30d/0x3f0
 ? __pfx_unregister_netdevice_queue+0x10/0x10
 ? __pfx_down_write+0x10/0x10
 unregister_netdev+0x1c/0x30
 bnep_session+0x1fb3/0x2ab0
 ? __pfx_bnep_session+0x10/0x10
 ? __pfx_lock_release+0x10/0x10
 ? __pfx_woken_wake_function+0x10/0x10
 ? __kthread_parkme+0x132/0x200
 ? __pfx_bnep_session+0x10/0x10
 ? kthread+0x13a/0x370
 ? __pfx_bnep_session+0x10/0x10
 kthread+0x2b7/0x370
 ? __pfx_kthread+0x10/0x10
 ret_from_fork+0x48/0x80
 ? __pfx_kthread+0x10/0x10
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Allocated by task 4974:
 kasan_save_stack+0x30/0x50
 kasan_save_track+0x14/0x30
 __kasan_kmalloc+0xaa/0xb0
 __kmalloc_noprof+0x1d1/0x440
 hci_alloc_dev_priv+0x1d/0x2820
 __vhci_create_device+0xef/0x7d0
 vhci_write+0x2c7/0x480
 vfs_write+0x6a0/0xfc0
 ksys_write+0x12f/0x260
 do_syscall_64+0xc7/0x250
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 4979:
 kasan_save_stack+0x30/0x50
 kasan_save_track+0x14/0x30
 kasan_save_free_info+0x3b/0x60
 __kasan_slab_free+0x4f/0x70
 kfree+0x141/0x490
 hci_release_dev+0x4d9/0x600
 bt_host_release+0x6a/0xb0
 device_release+0xa4/0x240
 kobject_put+0x1ec/0x5a0
 put_device+0x1f/0x30
 vhci_release+0x81/0xf0
 __fput+0x3f6/0xb30
 task_work_run+0x151/0x250
 do_exit+0xa79/0x2c30
 do_group_exit+0xd5/0x2a0
 get_signal+0x1fcd/0x2210
 arch_do_signal_or_restart+0x93/0x780
 syscall_exit_to_user_mode+0x140/0x290
 do_syscall_64+0xd4/0x250
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

In 'hci_conn_del_sysfs()', 'device_unregister()' may be called when
an underlying (kobject) reference counter is greater than 1. This
means that reparenting (happened when the device is actually freed)
is delayed and, during that delay, parent controller device (hciX)
may be deleted. Since the latter may create a dangling pointer to
freed parent, avoid that scenario by reparenting to NULL explicitly.

Reported-by: syzbot+6cf5652d3df49fae2e3f@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=6cf5652d3df49fae2e3f
Fixes: a85fb91e3d72 ("Bluetooth: Fix double free in hci_conn_cleanup")
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
---
v2: reparent per-connection 'struct device' explicitly
---
 net/bluetooth/hci_sysfs.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/bluetooth/hci_sysfs.c b/net/bluetooth/hci_sysfs.c
index 367e32fe30eb..80ac537fa500 100644
--- a/net/bluetooth/hci_sysfs.c
+++ b/net/bluetooth/hci_sysfs.c
@@ -73,6 +73,8 @@ void hci_conn_del_sysfs(struct hci_conn *conn)
 		return;
 	}
 
+	device_move(&conn->dev, NULL, DPM_ORDER_DEV_LAST);
+
 	while (1) {
 		struct device *dev;
 
-- 
2.47.0

Re: [PATCH v2] Bluetooth: fix use-after-free in device_for_each_child()

[Luiz Augusto von Dentz]

#syz test

On Fri, Nov 1, 2024 at 7:44 AM Dmitry Antipov <dmantipov@yandex.ru> wrote:
>
> Syzbot has reported the following KASAN splat:
>
> BUG: KASAN: slab-use-after-free in device_for_each_child+0x18f/0x1a0
> Read of size 8 at addr ffff88801f605308 by task kbnepd bnep0/4980
>
> CPU: 0 UID: 0 PID: 4980 Comm: kbnepd bnep0 Not tainted 6.12.0-rc4-00161-gae90f6a6170d #1
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-2.fc40 04/01/2014
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0x100/0x190
>  ? device_for_each_child+0x18f/0x1a0
>  print_report+0x13a/0x4cb
>  ? __virt_addr_valid+0x5e/0x590
>  ? __phys_addr+0xc6/0x150
>  ? device_for_each_child+0x18f/0x1a0
>  kasan_report+0xda/0x110
>  ? device_for_each_child+0x18f/0x1a0
>  ? __pfx_dev_memalloc_noio+0x10/0x10
>  device_for_each_child+0x18f/0x1a0
>  ? __pfx_device_for_each_child+0x10/0x10
>  pm_runtime_set_memalloc_noio+0xf2/0x180
>  netdev_unregister_kobject+0x1ed/0x270
>  unregister_netdevice_many_notify+0x123c/0x1d80
>  ? __mutex_trylock_common+0xde/0x250
>  ? __pfx_unregister_netdevice_many_notify+0x10/0x10
>  ? trace_contention_end+0xe6/0x140
>  ? __mutex_lock+0x4e7/0x8f0
>  ? __pfx_lock_acquire.part.0+0x10/0x10
>  ? rcu_is_watching+0x12/0xc0
>  ? unregister_netdev+0x12/0x30
>  unregister_netdevice_queue+0x30d/0x3f0
>  ? __pfx_unregister_netdevice_queue+0x10/0x10
>  ? __pfx_down_write+0x10/0x10
>  unregister_netdev+0x1c/0x30
>  bnep_session+0x1fb3/0x2ab0
>  ? __pfx_bnep_session+0x10/0x10
>  ? __pfx_lock_release+0x10/0x10
>  ? __pfx_woken_wake_function+0x10/0x10
>  ? __kthread_parkme+0x132/0x200
>  ? __pfx_bnep_session+0x10/0x10
>  ? kthread+0x13a/0x370
>  ? __pfx_bnep_session+0x10/0x10
>  kthread+0x2b7/0x370
>  ? __pfx_kthread+0x10/0x10
>  ret_from_fork+0x48/0x80
>  ? __pfx_kthread+0x10/0x10
>  ret_from_fork_asm+0x1a/0x30
>  </TASK>
>
> Allocated by task 4974:
>  kasan_save_stack+0x30/0x50
>  kasan_save_track+0x14/0x30
>  __kasan_kmalloc+0xaa/0xb0
>  __kmalloc_noprof+0x1d1/0x440
>  hci_alloc_dev_priv+0x1d/0x2820
>  __vhci_create_device+0xef/0x7d0
>  vhci_write+0x2c7/0x480
>  vfs_write+0x6a0/0xfc0
>  ksys_write+0x12f/0x260
>  do_syscall_64+0xc7/0x250
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> Freed by task 4979:
>  kasan_save_stack+0x30/0x50
>  kasan_save_track+0x14/0x30
>  kasan_save_free_info+0x3b/0x60
>  __kasan_slab_free+0x4f/0x70
>  kfree+0x141/0x490
>  hci_release_dev+0x4d9/0x600
>  bt_host_release+0x6a/0xb0
>  device_release+0xa4/0x240
>  kobject_put+0x1ec/0x5a0
>  put_device+0x1f/0x30
>  vhci_release+0x81/0xf0
>  __fput+0x3f6/0xb30
>  task_work_run+0x151/0x250
>  do_exit+0xa79/0x2c30
>  do_group_exit+0xd5/0x2a0
>  get_signal+0x1fcd/0x2210
>  arch_do_signal_or_restart+0x93/0x780
>  syscall_exit_to_user_mode+0x140/0x290
>  do_syscall_64+0xd4/0x250
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> In 'hci_conn_del_sysfs()', 'device_unregister()' may be called when
> an underlying (kobject) reference counter is greater than 1. This
> means that reparenting (happened when the device is actually freed)
> is delayed and, during that delay, parent controller device (hciX)
> may be deleted. Since the latter may create a dangling pointer to
> freed parent, avoid that scenario by reparenting to NULL explicitly.
>
> Reported-by: syzbot+6cf5652d3df49fae2e3f@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=6cf5652d3df49fae2e3f
> Fixes: a85fb91e3d72 ("Bluetooth: Fix double free in hci_conn_cleanup")
> Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
> ---
> v2: reparent per-connection 'struct device' explicitly
> ---
>  net/bluetooth/hci_sysfs.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/net/bluetooth/hci_sysfs.c b/net/bluetooth/hci_sysfs.c
> index 367e32fe30eb..80ac537fa500 100644
> --- a/net/bluetooth/hci_sysfs.c
> +++ b/net/bluetooth/hci_sysfs.c
> @@ -73,6 +73,8 @@ void hci_conn_del_sysfs(struct hci_conn *conn)
>                 return;
>         }
>
> +       device_move(&conn->dev, NULL, DPM_ORDER_DEV_LAST);
> +
>         while (1) {
>                 struct device *dev;
>
> --
> 2.47.0
>


-- 
Luiz Augusto von Dentz

Re: [PATCH v2] Bluetooth: fix use-after-free in device_for_each_child()

[Dmitry Antipov]

On 11/1/24 6:01 PM, Luiz Augusto von Dentz wrote:

> #syz test

Please see at https://syzkaller.appspot.com/bug?extid=6cf5652d3df49fae2e3f just as usual.

Dmitry

Re: [PATCH v2] Bluetooth: fix use-after-free in device_for_each_child()

[Luiz Augusto von Dentz]

Hi Dmitry,

On Fri, Nov 1, 2024 at 11:06 AM Dmitry Antipov <dmantipov@yandex.ru> wrote:
>
> On 11/1/24 6:01 PM, Luiz Augusto von Dentz wrote:
>
> > #syz test
>
> Please see at https://syzkaller.appspot.com/bug?extid=6cf5652d3df49fae2e3f just as usual.

There is no Tested-by thus why I assumed it wasn't tested by syzbot yet.

> Dmitry
>


-- 
Luiz Augusto von Dentz

Re: [PATCH v2] Bluetooth: fix use-after-free in device_for_each_child()

[Dmitry Antipov]

On 11/1/24 6:12 PM, Luiz Augusto von Dentz wrote:

> There is no Tested-by thus why I assumed it wasn't tested by syzbot yet.

Ugh. Until today I've assumed that Tested-by: is applicable to human-driven
testing only :-).

Dmitry

Re: [PATCH v2] Bluetooth: fix use-after-free in device_for_each_child()

[Luiz Augusto von Dentz]

Hi Dmitry,

On Fri, Nov 1, 2024 at 11:17 AM Dmitry Antipov <dmantipov@yandex.ru> wrote:
>
> On 11/1/24 6:12 PM, Luiz Augusto von Dentz wrote:
>
> > There is no Tested-by thus why I assumed it wasn't tested by syzbot yet.
>
> Ugh. Until today I've assumed that Tested-by: is applicable to human-driven
> testing only :-).

Nope, in fact it is very handy to have syzbot test your changes since
it may hit other problems as well.

> Dmitry
>


-- 
Luiz Augusto von Dentz

Re: [syzbot] [pm?] KASAN: use-after-free Read in netdev_unregister_kobject

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-use-after-free Read in netdev_unregister_kobject

==================================================================
BUG: KASAN: slab-use-after-free in device_for_each_child+0xbb/0x1b0 drivers/base/core.c:3999
Read of size 8 at addr ffff888021c81308 by task kbnepd bnep0/5597

CPU: 0 UID: 0 PID: 5597 Comm: kbnepd bnep0 Not tainted 6.12.0-rc5-syzkaller-00181-g6c52d4da1c74 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:488
 kasan_report+0x143/0x180 mm/kasan/report.c:601
 device_for_each_child+0xbb/0x1b0 drivers/base/core.c:3999
 pm_runtime_set_memalloc_noio+0x114/0x260 drivers/base/power/runtime.c:248
 netdev_unregister_kobject+0x178/0x250 net/core/net-sysfs.c:2109
 unregister_netdevice_many_notify+0x1851/0x1da0 net/core/dev.c:11441
 unregister_netdevice_many net/core/dev.c:11469 [inline]
 unregister_netdevice_queue+0x303/0x370 net/core/dev.c:11343
 unregister_netdevice include/linux/netdevice.h:3118 [inline]
 unregister_netdev+0x1c/0x30 net/core/dev.c:11487
 bnep_session+0x2e0e/0x3000 net/bluetooth/bnep/core.c:525
 kthread+0x2f2/0x390 kernel/kthread.c:389
 ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>

Allocated by task 5425:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:257 [inline]
 __do_kmalloc_node mm/slub.c:4264 [inline]
 __kmalloc_noprof+0x1fc/0x400 mm/slub.c:4276
 kmalloc_noprof include/linux/slab.h:882 [inline]
 kzalloc_noprof include/linux/slab.h:1014 [inline]
 hci_alloc_dev_priv+0x27/0x2030 net/bluetooth/hci_core.c:2440
 hci_alloc_dev include/net/bluetooth/hci_core.h:1621 [inline]
 __vhci_create_device drivers/bluetooth/hci_vhci.c:399 [inline]
 vhci_create_device+0x116/0x6a0 drivers/bluetooth/hci_vhci.c:470
 vhci_get_user drivers/bluetooth/hci_vhci.c:527 [inline]
 vhci_write+0x3cf/0x490 drivers/bluetooth/hci_vhci.c:607
 new_sync_write fs/read_write.c:590 [inline]
 vfs_write+0xaed/0xd30 fs/read_write.c:683
 ksys_write+0x183/0x2b0 fs/read_write.c:736
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5425:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:579
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_slab_free+0x59/0x70 mm/kasan/common.c:264
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:2342 [inline]
 slab_free mm/slub.c:4579 [inline]
 kfree+0x1a0/0x440 mm/slub.c:4727
 hci_release_dev+0x1525/0x16b0 net/bluetooth/hci_core.c:2759
 bt_host_release+0x83/0x90 net/bluetooth/hci_sysfs.c:94
 device_release+0x9b/0x1c0
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x231/0x480 lib/kobject.c:737
 vhci_release+0x88/0xd0 drivers/bluetooth/hci_vhci.c:665
 __fput+0x241/0x880 fs/file_table.c:431
 task_work_run+0x251/0x310 kernel/task_work.c:239
 exit_task_work include/linux/task_work.h:43 [inline]
 do_exit+0xa2f/0x28e0 kernel/exit.c:939
 do_group_exit+0x207/0x2c0 kernel/exit.c:1088
 __do_sys_exit_group kernel/exit.c:1099 [inline]
 __se_sys_exit_group kernel/exit.c:1097 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1097
 x64_sys_call+0x2634/0x2640 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Last potentially related work creation:
 kasan_save_stack+0x3f/0x60 mm/kasan/common.c:47
 __kasan_record_aux_stack+0xac/0xc0 mm/kasan/generic.c:541
 insert_work+0x3e/0x330 kernel/workqueue.c:2183
 __queue_work+0xb66/0xf50 kernel/workqueue.c:2343
 queue_work_on+0x1c2/0x380 kernel/workqueue.c:2390
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0xa65/0x1850 kernel/workqueue.c:3310
 worker_thread+0x870/0xd30 kernel/workqueue.c:3391
 kthread+0x2f2/0x390 kernel/kthread.c:389
 ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Second to last potentially related work creation:
 kasan_save_stack+0x3f/0x60 mm/kasan/common.c:47
 __kasan_record_aux_stack+0xac/0xc0 mm/kasan/generic.c:541
 insert_work+0x3e/0x330 kernel/workqueue.c:2183
 __queue_work+0xc8b/0xf50 kernel/workqueue.c:2339
 call_timer_fn+0x190/0x650 kernel/time/timer.c:1794
 expire_timers kernel/time/timer.c:1840 [inline]
 __run_timers kernel/time/timer.c:2419 [inline]
 __run_timer_base+0x695/0x8e0 kernel/time/timer.c:2430
 run_timer_base kernel/time/timer.c:2439 [inline]
 run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2449
 handle_softirqs+0x2c7/0x980 kernel/softirq.c:554
 __do_softirq kernel/softirq.c:588 [inline]
 invoke_softirq kernel/softirq.c:428 [inline]
 __irq_exit_rcu+0xf4/0x1c0 kernel/softirq.c:637
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:649
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1049
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702

The buggy address belongs to the object at ffff888021c80000
 which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 4872 bytes inside of
 freed 8192-byte region [ffff888021c80000, ffff888021c82000)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x21c80
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff888015442280 0000000000000000 0000000000000001
raw: 0000000000000000 0000000000020002 00000001f5000000 0000000000000000
head: 00fff00000000040 ffff888015442280 0000000000000000 0000000000000001
head: 0000000000000000 0000000000020002 00000001f5000000 0000000000000000
head: 00fff00000000003 ffffea0000872001 ffffffffffffffff 0000000000000000
head: 0000000000000008 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 4752, tgid 4752 (S40network), ts 32094841667, free_ts 32026397912
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1537
 prep_new_page mm/page_alloc.c:1545 [inline]
 get_page_from_freelist+0x303f/0x3190 mm/page_alloc.c:3457
 __alloc_pages_noprof+0x292/0x710 mm/page_alloc.c:4733
 alloc_pages_mpol_noprof+0x3e8/0x680 mm/mempolicy.c:2265
 alloc_slab_page+0x6a/0x120 mm/slub.c:2412
 allocate_slab+0x5a/0x2f0 mm/slub.c:2578
 new_slab mm/slub.c:2631 [inline]
 ___slab_alloc+0xcd1/0x14b0 mm/slub.c:3818
 __slab_alloc+0x58/0xa0 mm/slub.c:3908
 __slab_alloc_node mm/slub.c:3961 [inline]
 slab_alloc_node mm/slub.c:4122 [inline]
 __kmalloc_cache_noprof+0x1d5/0x2c0 mm/slub.c:4290
 kmalloc_noprof include/linux/slab.h:878 [inline]
 kzalloc_noprof include/linux/slab.h:1014 [inline]
 tomoyo_print_bprm security/tomoyo/audit.c:26 [inline]
 tomoyo_init_log+0x11cd/0x2050 security/tomoyo/audit.c:264
 tomoyo_supervisor+0x38a/0x11f0 security/tomoyo/common.c:2089
 tomoyo_audit_env_log security/tomoyo/environ.c:36 [inline]
 tomoyo_env_perm+0x178/0x210 security/tomoyo/environ.c:63
 tomoyo_environ security/tomoyo/domain.c:672 [inline]
 tomoyo_find_next_domain+0x146e/0x1d40 security/tomoyo/domain.c:881
 tomoyo_bprm_check_security+0x114/0x180 security/tomoyo/tomoyo.c:102
 security_bprm_check+0x86/0x250 security/security.c:1297
 search_binary_handler fs/exec.c:1740 [inline]
 exec_binprm fs/exec.c:1794 [inline]
 bprm_execve+0xa56/0x1770 fs/exec.c:1845
page last free pid 4751 tgid 4751 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1108 [inline]
 free_unref_page+0xcfb/0xf20 mm/page_alloc.c:2638
 __slab_free+0x31b/0x3d0 mm/slub.c:4490
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x9a/0x140 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x14f/0x170 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x23/0x80 mm/kasan/common.c:329
 kasan_slab_alloc include/linux/kasan.h:247 [inline]
 slab_post_alloc_hook mm/slub.c:4085 [inline]
 slab_alloc_node mm/slub.c:4134 [inline]
 kmem_cache_alloc_noprof+0x135/0x2a0 mm/slub.c:4141
 vm_area_alloc+0x24/0x1d0 kernel/fork.c:472
 mmap_region+0x1134/0x2940 mm/mmap.c:1436
 do_mmap+0x8f0/0x1000 mm/mmap.c:496
 vm_mmap_pgoff+0x1dd/0x3d0 mm/util.c:588
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888021c81200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888021c81280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888021c81300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff888021c81380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888021c81400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


Tested on:

commit:         6c52d4da Merge tag 'for-linus' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15e81630580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=2cf68159adbdf217
dashboard link: https://syzkaller.appspot.com/bug?extid=6cf5652d3df49fae2e3f
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Note: no patches were applied.

Re: [PATCH v2] Bluetooth: fix use-after-free in device_for_each_child()

[Luiz Augusto von Dentz]

Hi Dmitry,

On Fri, Nov 1, 2024 at 11:31 AM Luiz Augusto von Dentz
<luiz.dentz@gmail.com> wrote:
>
> Hi Dmitry,
>
> On Fri, Nov 1, 2024 at 11:17 AM Dmitry Antipov <dmantipov@yandex.ru> wrote:
> >
> > On 11/1/24 6:12 PM, Luiz Augusto von Dentz wrote:
> >
> > > There is no Tested-by thus why I assumed it wasn't tested by syzbot yet.
> >
> > Ugh. Until today I've assumed that Tested-by: is applicable to human-driven
> > testing only :-).
>
> Nope, in fact it is very handy to have syzbot test your changes since
> it may hit other problems as well.

Looks like this doesn't solve the problem, in fact I think you are
getting it backwards, you are trying to reparent the parent dev not
the child and I assume by destroying the parent device there should be
some way to reset the parent which seems to be the intent the
following code in hci_conn_del_sysfs:

    while (1) {
        struct device *dev;

        dev = device_find_child(&conn->dev, NULL, __match_tty);
        if (!dev)
            break;
        device_move(dev, NULL, DPM_ORDER_DEV_LAST);
        put_device(dev);
    }

But note that it only does that after matching tty, but I guess we
want to do it regardless otherwise we may have the child objects still
access it, that said we should probably use device_for_each_child
though if that is safe to do calls to device_move under its callback.

> > Dmitry
> >
>
>
> --
> Luiz Augusto von Dentz



-- 
Luiz Augusto von Dentz

Re: [PATCH v2] Bluetooth: fix use-after-free in device_for_each_child()

[Luiz Augusto von Dentz]

[-- Attachment #1: Type: text/plain, Size: 1727 bytes --]

On Fri, Nov 1, 2024 at 1:37 PM Luiz Augusto von Dentz
<luiz.dentz@gmail.com> wrote:
>
> Hi Dmitry,
>
> On Fri, Nov 1, 2024 at 11:31 AM Luiz Augusto von Dentz
> <luiz.dentz@gmail.com> wrote:
> >
> > Hi Dmitry,
> >
> > On Fri, Nov 1, 2024 at 11:17 AM Dmitry Antipov <dmantipov@yandex.ru> wrote:
> > >
> > > On 11/1/24 6:12 PM, Luiz Augusto von Dentz wrote:
> > >
> > > > There is no Tested-by thus why I assumed it wasn't tested by syzbot yet.
> > >
> > > Ugh. Until today I've assumed that Tested-by: is applicable to human-driven
> > > testing only :-).
> >
> > Nope, in fact it is very handy to have syzbot test your changes since
> > it may hit other problems as well.
>
> Looks like this doesn't solve the problem, in fact I think you are
> getting it backwards, you are trying to reparent the parent dev not
> the child and I assume by destroying the parent device there should be
> some way to reset the parent which seems to be the intent the
> following code in hci_conn_del_sysfs:
>
>     while (1) {
>         struct device *dev;
>
>         dev = device_find_child(&conn->dev, NULL, __match_tty);
>         if (!dev)
>             break;
>         device_move(dev, NULL, DPM_ORDER_DEV_LAST);
>         put_device(dev);
>     }
>
> But note that it only does that after matching tty, but I guess we
> want to do it regardless otherwise we may have the child objects still
> access it, that said we should probably use device_for_each_child
> though if that is safe to do calls to device_move under its callback.

#syz test

> > > Dmitry
> > >
> >
> >
> > --
> > Luiz Augusto von Dentz
>
>
>
> --
> Luiz Augusto von Dentz



-- 
Luiz Augusto von Dentz

[-- Attachment #2: v1-0001-Bluetooth-fix-use-after-free-in-device_for_each_c.patch --]
[-- Type: text/x-patch, Size: 4217 bytes --]

From fe0a0db8a272b73c61a957adccaf3038f65d77fa Mon Sep 17 00:00:00 2001
From: Dmitry Antipov <dmantipov@yandex.ru>
Date: Fri, 1 Nov 2024 14:44:10 +0300
Subject: [PATCH v1] Bluetooth: fix use-after-free in device_for_each_child()

Syzbot has reported the following KASAN splat:

BUG: KASAN: slab-use-after-free in device_for_each_child+0x18f/0x1a0
Read of size 8 at addr ffff88801f605308 by task kbnepd bnep0/4980

CPU: 0 UID: 0 PID: 4980 Comm: kbnepd bnep0 Not tainted 6.12.0-rc4-00161-gae90f6a6170d #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-2.fc40 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x100/0x190
 ? device_for_each_child+0x18f/0x1a0
 print_report+0x13a/0x4cb
 ? __virt_addr_valid+0x5e/0x590
 ? __phys_addr+0xc6/0x150
 ? device_for_each_child+0x18f/0x1a0
 kasan_report+0xda/0x110
 ? device_for_each_child+0x18f/0x1a0
 ? __pfx_dev_memalloc_noio+0x10/0x10
 device_for_each_child+0x18f/0x1a0
 ? __pfx_device_for_each_child+0x10/0x10
 pm_runtime_set_memalloc_noio+0xf2/0x180
 netdev_unregister_kobject+0x1ed/0x270
 unregister_netdevice_many_notify+0x123c/0x1d80
 ? __mutex_trylock_common+0xde/0x250
 ? __pfx_unregister_netdevice_many_notify+0x10/0x10
 ? trace_contention_end+0xe6/0x140
 ? __mutex_lock+0x4e7/0x8f0
 ? __pfx_lock_acquire.part.0+0x10/0x10
 ? rcu_is_watching+0x12/0xc0
 ? unregister_netdev+0x12/0x30
 unregister_netdevice_queue+0x30d/0x3f0
 ? __pfx_unregister_netdevice_queue+0x10/0x10
 ? __pfx_down_write+0x10/0x10
 unregister_netdev+0x1c/0x30
 bnep_session+0x1fb3/0x2ab0
 ? __pfx_bnep_session+0x10/0x10
 ? __pfx_lock_release+0x10/0x10
 ? __pfx_woken_wake_function+0x10/0x10
 ? __kthread_parkme+0x132/0x200
 ? __pfx_bnep_session+0x10/0x10
 ? kthread+0x13a/0x370
 ? __pfx_bnep_session+0x10/0x10
 kthread+0x2b7/0x370
 ? __pfx_kthread+0x10/0x10
 ret_from_fork+0x48/0x80
 ? __pfx_kthread+0x10/0x10
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Allocated by task 4974:
 kasan_save_stack+0x30/0x50
 kasan_save_track+0x14/0x30
 __kasan_kmalloc+0xaa/0xb0
 __kmalloc_noprof+0x1d1/0x440
 hci_alloc_dev_priv+0x1d/0x2820
 __vhci_create_device+0xef/0x7d0
 vhci_write+0x2c7/0x480
 vfs_write+0x6a0/0xfc0
 ksys_write+0x12f/0x260
 do_syscall_64+0xc7/0x250
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 4979:
 kasan_save_stack+0x30/0x50
 kasan_save_track+0x14/0x30
 kasan_save_free_info+0x3b/0x60
 __kasan_slab_free+0x4f/0x70
 kfree+0x141/0x490
 hci_release_dev+0x4d9/0x600
 bt_host_release+0x6a/0xb0
 device_release+0xa4/0x240
 kobject_put+0x1ec/0x5a0
 put_device+0x1f/0x30
 vhci_release+0x81/0xf0
 __fput+0x3f6/0xb30
 task_work_run+0x151/0x250
 do_exit+0xa79/0x2c30
 do_group_exit+0xd5/0x2a0
 get_signal+0x1fcd/0x2210
 arch_do_signal_or_restart+0x93/0x780
 syscall_exit_to_user_mode+0x140/0x290
 do_syscall_64+0xd4/0x250
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

In 'hci_conn_del_sysfs()', 'device_unregister()' may be called when
an underlying (kobject) reference counter is greater than 1. This
means that reparenting (happened when the device is actually freed)
is delayed and, during that delay, parent controller device (hciX)
may be deleted. Since the latter may create a dangling pointer to
freed parent, avoid that scenario by reparenting to NULL explicitly.

Reported-by: syzbot+6cf5652d3df49fae2e3f@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=6cf5652d3df49fae2e3f
Fixes: a85fb91e3d72 ("Bluetooth: Fix double free in hci_conn_cleanup")
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
---
 net/bluetooth/hci_sysfs.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/bluetooth/hci_sysfs.c b/net/bluetooth/hci_sysfs.c
index 367e32fe30eb..da74b38637ce 100644
--- a/net/bluetooth/hci_sysfs.c
+++ b/net/bluetooth/hci_sysfs.c
@@ -73,10 +73,13 @@ void hci_conn_del_sysfs(struct hci_conn *conn)
 		return;
 	}
 
+	/* If there are devices using the connection as parent reset it to NULL
+	 * before unregistering the device.
+	 */
 	while (1) {
 		struct device *dev;
 
-		dev = device_find_child(&conn->dev, NULL, __match_tty);
+		dev = device_find_any_child(&conn->dev);
 		if (!dev)
 			break;
 		device_move(dev, NULL, DPM_ORDER_DEV_LAST);
-- 
2.47.0

Re: [syzbot] [pm?] KASAN: use-after-free Read in netdev_unregister_kobject

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+6cf5652d3df49fae2e3f@syzkaller.appspotmail.com
Tested-by: syzbot+6cf5652d3df49fae2e3f@syzkaller.appspotmail.com

Tested on:

commit:         c4264568 Merge tag 'acpi-6.12-rc6' of git://git.kernel..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=148ad340580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=2cf68159adbdf217
dashboard link: https://syzkaller.appspot.com/bug?extid=6cf5652d3df49fae2e3f
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1122d340580000

Note: testing is done by a robot and is best-effort only.

Re: [PATCH v2] Bluetooth: fix use-after-free in device_for_each_child()

[Dmitry Antipov]

On 11/1/24 8:37 PM, Luiz Augusto von Dentz wrote:

> Looks like this doesn't solve the problem, in fact I think you are
> getting it backwards, you are trying to reparent the parent dev not
> the child and I assume by destroying the parent device there should be
> some way to reset the parent which seems to be the intent the
> following code in hci_conn_del_sysfs:
> 
>      while (1) {
>          struct device *dev;
> 
>          dev = device_find_child(&conn->dev, NULL, __match_tty);
>          if (!dev)
>              break;
>          device_move(dev, NULL, DPM_ORDER_DEV_LAST);
>          put_device(dev);
>      }
> 
> But note that it only does that after matching tty, but I guess we
> want to do it regardless otherwise we may have the child objects still
> access it, that said we should probably use device_for_each_child
> though if that is safe to do calls to device_move under its callback.

I'm not sure that I've got your point. IIUC the problem is that a controller
(parent) instance may be freed _after_ the child (connection) has passed
'device_unregister(&conn->dev)' but _before_ an actual removal of 'conn->dev'
from the devices hierarchy, thus leaving the dangling 'conn->dev.parent'
pointer. The latter may be fixed by reparenting 'conn->dev' to NULL explicitly.
And handling children of 'conn->dev' (i.e. the grandchilren of the controller)
is out of this problem's scope at all.

And nothing to say about syzbot's innards but manual testing shows that the
following thing:

void hci_conn_del_sysfs(struct hci_conn *conn)
{
         struct hci_dev *hdev = conn->hdev;

         bt_dev_dbg(hdev, "conn %p", conn);

         if (!device_is_registered(&conn->dev)) {
                 /* If device_add() has *not* succeeded, use *only* put_device()
                  * to drop the reference count.
                  */
                 put_device(&conn->dev);
                 return;
         }

         while (1) {
                 struct device *dev;

                 dev = device_find_any_child(&conn->dev);
                 if (!dev)
                         break;
                 printk(KERN_ERR "%s:%d: reparent dev@%p(%s) with parent@%p(%s)\n",
                        __FILE__, __LINE__, dev, dev_name(dev), dev->parent,
                        (dev->parent ? dev_name(dev->parent) : "<none>"));
                 device_move(dev, NULL, DPM_ORDER_DEV_LAST);
                 put_device(dev);
         }

         device_unregister(&conn->dev);
}

occasionally triggers the following crash:

net/bluetooth/hci_sysfs.c:82: reparent dev@ffff888114be86f8(bnep0) with parent@ffff888111c64b68(hci4:200)
Oops: general protection fault, probably for non-canonical address 0xdffffc000000000b: 0000 [#1] PREEMPT SMP KASI
KASAN: null-ptr-deref in range [0x0000000000000058-0x000000000000005f]
CPU: 3 UID: 0 PID: 6033 Comm: repro Not tainted 6.12.0-rc5-00299-g11066801dd4b-dirty #8
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-3.fc41 04/01/2014
RIP: 0010:klist_put+0x4d/0x1d0
Code: c1 ea 03 80 3c 02 00 0f 85 74 01 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b 23 49 83 e4 fe 49 8d 7c 24 58 49
RSP: 0018:ffffc9000423f9b0 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff88810f43ac60 RCX: 0000000000000000
RDX: 000000000000000b RSI: ffffffff8a92d415 RDI: 0000000000000058
RBP: 0000000000000001 R08: 0000000000000000 R09: fffffbfff1fad62c
R10: ffffffff8fd6b163 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000001 R14: ffffc9000423fa30 R15: ffffffff8a92d805
FS:  00007f24ebb78740(0000) GS:ffff888135f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055c52afb6950 CR3: 0000000020c1c000 CR4: 00000000000006f0
Call Trace:
  <TASK>
  ? die_addr.cold+0x8/0xd
  ? exc_general_protection+0x147/0x240
  ? asm_exc_general_protection+0x26/0x30
  ? klist_remove+0x155/0x2b0
  ? klist_put+0x15/0x1d0
  ? klist_put+0x4d/0x1d0
  klist_remove+0x15a/0x2b0
  ? __pfx_klist_remove+0x10/0x10
  device_move+0x12d/0x10b0
  hci_conn_del_sysfs.cold+0xcf/0x14a
  hci_conn_del+0x467/0xd60
  hci_conn_hash_flush+0x18f/0x270
  hci_dev_close_sync+0x549/0x1260
  hci_dev_do_close+0x2e/0x90
  hci_unregister_dev+0x213/0x630
  vhci_release+0x79/0xf0
  ? __pfx_vhci_release+0x10/0x10
  __fput+0x3f6/0xb30
  task_work_run+0x151/0x250
  ? __pfx_task_work_run+0x10/0x10
  do_exit+0xa79/0x2c30
  ? do_raw_spin_lock+0x12a/0x2b0
  ? __pfx_do_exit+0x10/0x10
  do_group_exit+0xd5/0x2a0
  __x64_sys_exit_group+0x3e/0x50
  x64_sys_call+0x14af/0x14b0
  do_syscall_64+0xc7/0x250
  entry_SYSCALL_64_after_hwframe+0x77/0x7f

Dmitry

Re: [PATCH v2] Bluetooth: fix use-after-free in device_for_each_child()

[Luiz Augusto von Dentz]

Hi Dmitry,

On Sat, Nov 2, 2024 at 5:51 AM Dmitry Antipov <dmantipov@yandex.ru> wrote:
>
> On 11/1/24 8:37 PM, Luiz Augusto von Dentz wrote:
>
> > Looks like this doesn't solve the problem, in fact I think you are
> > getting it backwards, you are trying to reparent the parent dev not
> > the child and I assume by destroying the parent device there should be
> > some way to reset the parent which seems to be the intent the
> > following code in hci_conn_del_sysfs:
> >
> >      while (1) {
> >          struct device *dev;
> >
> >          dev = device_find_child(&conn->dev, NULL, __match_tty);
> >          if (!dev)
> >              break;
> >          device_move(dev, NULL, DPM_ORDER_DEV_LAST);
> >          put_device(dev);
> >      }
> >
> > But note that it only does that after matching tty, but I guess we
> > want to do it regardless otherwise we may have the child objects still
> > access it, that said we should probably use device_for_each_child
> > though if that is safe to do calls to device_move under its callback.
>
> I'm not sure that I've got your point. IIUC the problem is that a controller
> (parent) instance may be freed _after_ the child (connection) has passed
> 'device_unregister(&conn->dev)' but _before_ an actual removal of 'conn->dev'
> from the devices hierarchy, thus leaving the dangling 'conn->dev.parent'
> pointer. The latter may be fixed by reparenting 'conn->dev' to NULL explicitly.
> And handling children of 'conn->dev' (i.e. the grandchilren of the controller)
> is out of this problem's scope at all.
>
> And nothing to say about syzbot's innards but manual testing shows that the
> following thing:
>
> void hci_conn_del_sysfs(struct hci_conn *conn)
> {
>          struct hci_dev *hdev = conn->hdev;
>
>          bt_dev_dbg(hdev, "conn %p", conn);
>
>          if (!device_is_registered(&conn->dev)) {
>                  /* If device_add() has *not* succeeded, use *only* put_device()
>                   * to drop the reference count.
>                   */
>                  put_device(&conn->dev);
>                  return;
>          }
>
>          while (1) {
>                  struct device *dev;
>
>                  dev = device_find_any_child(&conn->dev);
>                  if (!dev)
>                          break;
>                  printk(KERN_ERR "%s:%d: reparent dev@%p(%s) with parent@%p(%s)\n",
>                         __FILE__, __LINE__, dev, dev_name(dev), dev->parent,
>                         (dev->parent ? dev_name(dev->parent) : "<none>"));
>                  device_move(dev, NULL, DPM_ORDER_DEV_LAST);
>                  put_device(dev);
>          }
>
>          device_unregister(&conn->dev);
> }
>
> occasionally triggers the following crash:
>
> net/bluetooth/hci_sysfs.c:82: reparent dev@ffff888114be86f8(bnep0) with parent@ffff888111c64b68(hci4:200)
> Oops: general protection fault, probably for non-canonical address 0xdffffc000000000b: 0000 [#1] PREEMPT SMP KASI
> KASAN: null-ptr-deref in range [0x0000000000000058-0x000000000000005f]
> CPU: 3 UID: 0 PID: 6033 Comm: repro Not tainted 6.12.0-rc5-00299-g11066801dd4b-dirty #8
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-3.fc41 04/01/2014
> RIP: 0010:klist_put+0x4d/0x1d0
> Code: c1 ea 03 80 3c 02 00 0f 85 74 01 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b 23 49 83 e4 fe 49 8d 7c 24 58 49
> RSP: 0018:ffffc9000423f9b0 EFLAGS: 00010202
> RAX: dffffc0000000000 RBX: ffff88810f43ac60 RCX: 0000000000000000
> RDX: 000000000000000b RSI: ffffffff8a92d415 RDI: 0000000000000058
> RBP: 0000000000000001 R08: 0000000000000000 R09: fffffbfff1fad62c
> R10: ffffffff8fd6b163 R11: 0000000000000000 R12: 0000000000000000
> R13: 0000000000000001 R14: ffffc9000423fa30 R15: ffffffff8a92d805
> FS:  00007f24ebb78740(0000) GS:ffff888135f00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 000055c52afb6950 CR3: 0000000020c1c000 CR4: 00000000000006f0
> Call Trace:
>   <TASK>
>   ? die_addr.cold+0x8/0xd
>   ? exc_general_protection+0x147/0x240
>   ? asm_exc_general_protection+0x26/0x30
>   ? klist_remove+0x155/0x2b0
>   ? klist_put+0x15/0x1d0
>   ? klist_put+0x4d/0x1d0
>   klist_remove+0x15a/0x2b0
>   ? __pfx_klist_remove+0x10/0x10
>   device_move+0x12d/0x10b0
>   hci_conn_del_sysfs.cold+0xcf/0x14a
>   hci_conn_del+0x467/0xd60
>   hci_conn_hash_flush+0x18f/0x270
>   hci_dev_close_sync+0x549/0x1260
>   hci_dev_do_close+0x2e/0x90
>   hci_unregister_dev+0x213/0x630
>   vhci_release+0x79/0xf0
>   ? __pfx_vhci_release+0x10/0x10
>   __fput+0x3f6/0xb30
>   task_work_run+0x151/0x250
>   ? __pfx_task_work_run+0x10/0x10
>   do_exit+0xa79/0x2c30
>   ? do_raw_spin_lock+0x12a/0x2b0
>   ? __pfx_do_exit+0x10/0x10
>   do_group_exit+0xd5/0x2a0
>   __x64_sys_exit_group+0x3e/0x50
>   x64_sys_call+0x14af/0x14b0
>   do_syscall_64+0xc7/0x250
>   entry_SYSCALL_64_after_hwframe+0x77/0x7f

Weird, this was not reproduced by syzbot when I asked it to test, how
are you reproducing this? This looks like to be a problem with klist
being corrupted somehow, anyway if we can't unparent the objects we
need a way to unregister the child without waiting for the bnep thread
to clean it up.

> Dmitry



-- 
Luiz Augusto von Dentz

Re: [PATCH v2] Bluetooth: fix use-after-free in device_for_each_child()

[Dmitry Antipov]

On 11/4/24 5:06 PM, Luiz Augusto von Dentz wrote:

> Weird, this was not reproduced by syzbot when I asked it to test, how
> are you reproducing this? 

This is not regular, looks like a race, and I'm not sure how many runs
are required to reproduce. Anyway we can't blame syzbot just because
it was unable to reproduce some weird thing.

Dmitry

Re: [PATCH v2] Bluetooth: fix use-after-free in device_for_each_child()

[Luiz Augusto von Dentz]

Hi,

On Mon, Nov 4, 2024 at 9:58 AM Dmitry Antipov <dmantipov@yandex.ru> wrote:
>
> On 11/4/24 5:06 PM, Luiz Augusto von Dentz wrote:
>
> > Weird, this was not reproduced by syzbot when I asked it to test, how
> > are you reproducing this?
>
> This is not regular, looks like a race, and I'm not sure how many runs
> are required to reproduce. Anyway we can't blame syzbot just because
> it was unable to reproduce some weird thing.

But how you reproducing, or you just running syzbot test over and over
locally? Anyway I will look into how we can actually unregister the
likes of bnep net_dev in a more direct manner rather than doing via
bnep kthread.

> Dmitry
>


-- 
Luiz Augusto von Dentz