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Date: Mon, 27 Feb 2023 15:58:31 -0800
From: Zhengping Jiang <jiangzp@...gle.com>
To: Luiz Augusto von Dentz <luiz.dentz@...il.com>
Cc: linux-bluetooth@...r.kernel.org, marcel@...tmann.org,
mmandlik@...gle.com, chromeos-bluetooth-upstreaming@...omium.org,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Johan Hedberg <johan.hedberg@...il.com>,
Paolo Abeni <pabeni@...hat.com>, linux-kernel@...r.kernel.org,
netdev@...r.kernel.org
Subject: Re: [kernel PATCH v2 1/1] Bluetooth: hci_sync: clear workqueue before
clear mgmt cmd
Hi Luiz,
Sure. Hope this helps.
Here is one log from the user.
[ 53.368740] ==================================================================
[ 53.376167] BUG: KASAN: use-after-free in set_ssp_sync+0x44/0x154 [bluetooth]
[ 53.384303] Read of size 8 at addr ffffff80b7ee0318 by task kworker/u17:0/190
[ 53.396342] CPU: 7 PID: 190 Comm: kworker/u17:0 Tainted: G W
5.15.59-lockdep #1 29eed131ef0afd42bc369a6a0ca1c69d3653699b
[ 53.408868] Hardware name: Qualcomm Technologies, Inc. sc7280 CRD
platform (rev5+) (DT)
[ 53.417095] Workqueue: hci0 hci_cmd_sync_work [bluetooth]
[ 53.422780] Call trace:
[ 53.425310] dump_backtrace+0x0/0x424
[ 53.429108] show_stack+0x20/0x2c
[ 53.432534] dump_stack_lvl+0x84/0xb4
[ 53.436514] print_address_description+0x30/0x2fc
[ 53.441369] kasan_report+0x15c/0x19c
[ 53.445975] __asan_report_load8_noabort+0x44/0x50
[ 53.450910] set_ssp_sync+0x44/0x154 [bluetooth
34f6fa2bbf49f3d7faf6ea04e8755ae16590a6b3]
[ 53.460136] hci_cmd_sync_work+0x1c8/0x2c8 [bluetooth
34f6fa2bbf49f3d7faf6ea04e8755ae16590a6b3]
[ 53.472214] process_one_work+0x59c/0xa88
[ 53.476990] worker_thread+0x81c/0xd18
[ 53.480854] kthread+0x2d4/0x3d8
[ 53.484272] ret_from_fork+0x10/0x20
[ 53.489733] Allocated by task 1162:
[ 53.493336] kasan_save_stack+0x38/0x68
[ 53.498115] __kasan_kmalloc+0xb4/0xd0
[ 53.501993] kmem_cache_alloc_trace+0x29c/0x374
[ 53.506661] mgmt_pending_new+0x74/0x200 [bluetooth]
[ 53.511905] mgmt_pending_add+0x28/0xec [bluetooth]
[ 53.517059] set_ssp+0x2d8/0x5b0 [bluetooth]
[ 53.521575] hci_mgmt_cmd+0x5c4/0x8b0 [bluetooth]
[ 53.526538] hci_sock_sendmsg+0x28c/0x95c [bluetooth]
[ 53.531850] sock_sendmsg+0xb4/0xd8
[ 53.535454] sock_write_iter+0x1c0/0x2d0
[ 53.539494] do_iter_readv_writev+0x350/0x4e0
[ 53.543980] do_iter_write+0xf0/0x2e4
[ 53.547747] vfs_writev+0xd0/0x13c
[ 53.551254] do_writev+0xe8/0x1fc
[ 53.554672] __arm64_sys_writev+0x84/0x98
[ 53.558805] invoke_syscall+0x78/0x20c
[ 53.562665] el0_svc_common+0x12c/0x2f0
[ 53.566618] do_el0_svc+0x94/0x13c
[ 53.570125] el0_svc+0x5c/0x108
[ 53.573374] el0t_64_sync_handler+0x78/0x108
[ 53.577773] el0t_64_sync+0x1a4/0x1a8
[ 53.583089] Freed by task 3207:
[ 53.586325] kasan_save_stack+0x38/0x68
[ 53.590282] kasan_set_track+0x28/0x3c
[ 53.594153] kasan_set_free_info+0x28/0x4c
[ 53.598369] ____kasan_slab_free+0x138/0x17c
[ 53.602767] __kasan_slab_free+0x18/0x28
[ 53.606803] slab_free_freelist_hook+0x188/0x260
[ 53.611559] kfree+0x138/0x29c
[ 53.614708] mgmt_pending_free+0xac/0xdc [bluetooth]
[ 53.619948] mgmt_pending_remove+0xd8/0xf0 [bluetooth]
[ 53.625357] cmd_complete_rsp+0xc8/0x178 [bluetooth]
[ 53.630586] mgmt_pending_foreach+0xa8/0xf8 [bluetooth]
[ 53.636076] __mgmt_power_off+0x114/0x26c [bluetooth]
[ 53.641390] hci_dev_close_sync+0x314/0x814 [bluetooth]
[ 53.646882] hci_dev_do_close+0x3c/0x7c [bluetooth]
[ 53.652017] hci_dev_close+0xa4/0x15c [bluetooth]
[ 53.656980] hci_sock_ioctl+0x298/0x444 [bluetooth]
[ 53.662117] sock_do_ioctl+0xd0/0x1e8
[ 53.665900] sock_ioctl+0x4fc/0x72c
[ 53.669500] __arm64_sys_ioctl+0x118/0x154
[ 53.673726] invoke_syscall+0x78/0x20c
[ 53.677587] el0_svc_common+0x12c/0x2f0
[ 53.681533] do_el0_svc+0x94/0x13c
[ 53.685043] el0_svc+0x5c/0x108
[ 53.688278] el0t_64_sync_handler+0x78/0x108
[ 53.692677] el0t_64_sync+0x1a4/0x1a8
[ 53.697988] Last potentially related work creation:
[ 53.703009] kasan_save_stack+0x38/0x68
[ 53.706962] kasan_record_aux_stack+0x104/0x130
[ 53.711622] __call_rcu+0x14c/0x860
[ 53.715212] call_rcu+0x18/0x24
[ 53.718448] sk_filter_uncharge+0xc0/0x120
[ 53.722667] __sk_destruct+0xb4/0x4a8
[ 53.726435] sk_destruct+0x78/0xa0
[ 53.729941] __sk_free+0x190/0x270
[ 53.733453] sk_free+0x54/0x8c
[ 53.736603] deferred_put_nlk_sk+0x1d4/0x20c
[ 53.741000] rcu_do_batch+0x3e8/0xd08
[ 53.744772] nocb_cb_wait+0xc8/0xa3c
[ 53.748453] rcu_nocb_cb_kthread+0x48/0x134
[ 53.752768] kthread+0x2d4/0x3d8
[ 53.756098] ret_from_fork+0x10/0x20
This is another one at a different function but with the same signature.
[ 43.363512] ==================================================================
[ 43.370966] BUG: KASAN: use-after-free in
mgmt_remove_adv_monitor_sync+0x40/0xcc [bluetooth]
[ 43.379813] Read of size 8 at addr ffffff8096c28d18 by task kworker/u17:0/192
[ 43.387158]
[ 43.388705] CPU: 6 PID: 192 Comm: kworker/u17:0 Tainted: G W
5.15.59-lockdep #1 59f35e3dfc07f6688b084869895c7a39892c891a
localhost ~ # [ 43.410184] Workqueue: hci0 hci_cmd_sync_work [bluetooth]
[ 43.418887] Call trace:
[ 43.422407] dump_backtrace+0x0/0x424
[ 43.426191] show_stack+0x20/0x2c
[ 43.429608] dump_stack_lvl+0x84/0xb4
[ 43.433395] print_address_description+0x30/0x2fc
[ 43.438243] kasan_report+0x15c/0x19c
[ 43.442070] __asan_report_load8_noabort+0x44/0x50
hciconfig hci0 up
[ 43.447009] mgmt_remove_adv_monitor_sync+0x40/0xcc [bluetooth
8dae3a82177133cfa9626e7322b3b0c8f665102d]
[ 43.458568] hci_cmd_sync_work+0x1bc/0x2bc [bluetooth
8dae3a82177133cfa9626e7322b3b0c8f665102d]
[ 43.467656] process_one_work+0x59c/0xa88
[ 43.472530] worker_thread+0x81c/0xd18
[ 43.476410] kthread+0x2d4/0x3d8
localhost ~ # [ 43.479753] ret_from_fork+0x10/0x20
[ 43.486588]
[ 43.488156] Allocated by task 1118:
[ 43.491751] kasan_save_stack+0x38/0x68
[ 43.495709] __kasan_kmalloc+0xb4/0xd0
[ 43.499577] kmem_cache_alloc_trace+0x29c/0x374
[ 43.504238] mgmt_pending_new+0x74/0x200 [bluetooth]
sleep 2[ 43.509509] mgmt_pending_add+0x28/0xec [bluetooth]
[ 43.515244] remove_adv_monitor+0xf8/0x174 [bluetooth]
[ 43.521533] hci_mgmt_cmd+0x5c4/0x8b0 [bluetooth]
[ 43.526527] hci_sock_sendmsg+0x28c/0x95c [bluetooth]
[ 43.531873] sock_sendmsg+0xb4/0xd8
[ 43.535472] sock_write_iter+0x1c0/0x2d0
[ 43.539519] do_iter_readv_writev+0x350/0x4e0
[ 43.544012] do_iter_write+0xf0/0x2e4
[ 43.547788] vfs_writev+0xd0/0x13c
[ 43.551295] do_writev+0xe8/0x1fc
[ 43.554710] __arm64_sys_writev+0x84/0x98
[ 43.558838] invoke_syscall+0x78/0x20c
[ 43.562709] el0_svc_common+0x12c/0x2f0
[ 43.566654] do_el0_svc+0x94/0x13c
[ 43.570155] el0_svc+0x5c/0x108
[ 43.573391] el0t_64_sync_handler+0x78/0x108
[ 43.577785] el0t_64_sync+0x1a4/0x1a8
[ 43.581564]
[ 43.583115] Freed by task 3217:
[ 43.586356] kasan_save_stack+0x38/0x68
[ 43.590314] kasan_set_track+0x28/0x3c
[ 43.594180] kasan_set_free_info+0x28/0x4c
[ 43.598396] ____kasan_slab_free+0x138/0x17c
[ 43.602794] __kasan_slab_free+0x18/0x28
[ 43.606838] slab_free_freelist_hook+0x188/0x260
[ 43.611591] kfree+0x138/0x29c
[ 43.614741] mgmt_pending_free+0xac/0xdc [bluetooth]
[ 43.620003] mgmt_pending_remove+0xd8/0xf0 [bluetooth]
[ 43.625434] cmd_complete_rsp+0xc8/0x178 [bluetooth]
[ 43.630686] mgmt_pending_foreach+0xa8/0xf8 [bluetooth]
[ 43.636198] __mgmt_power_off+0x114/0x26c [bluetooth]
[ 43.641532] hci_dev_close_sync+0x2ec/0x7ec [bluetooth]
[ 43.647049] hci_dev_do_close+0x3c/0x7c [bluetooth]
[ 43.652209] hci_dev_close+0xac/0x164 [bluetooth]
[ 43.657190] hci_sock_ioctl+0x298/0x444 [bluetooth]
[ 43.662353] sock_do_ioctl+0xd0/0x1e8
[ 43.666134] sock_ioctl+0x4fc/0x72c
[ 43.669736] __arm64_sys_ioctl+0x118/0x154
[ 43.673961] invoke_syscall+0x78/0x20c
[ 43.677820] el0_svc_common+0x12c/0x2f0
[ 43.681770] do_el0_svc+0x94/0x13c
[ 43.685278] el0_svc+0x5c/0x108
[ 43.688514] el0t_64_sync_handler+0x78/0x108
[ 43.692913] el0t_64_sync+0x1a4/0x1a8
Thanks,
Zhengping
On Mon, Feb 27, 2023 at 3:41 PM Luiz Augusto von Dentz
<luiz.dentz@...il.com> wrote:
>
> Hi Zhengping,
>
> On Sun, Feb 26, 2023 at 11:18 PM Zhengping Jiang <jiangzp@...gle.com> wrote:
> >
> > Hi Luiz,
> >
> > I have a question. Given that each command in the cmd_sync queue
> > should clean up the memory in a callback function. I was wondering if
> > the call to cmd_complete_rsp in __mgmt_power_off function is still
> > necessary? Will this always risk a race condition that cmd has been
> > released when the complete callback or _sync function is run?
>
> Not sure I follow you here, do you have a stack trace when the user
> after free occurs?
>
> > Thanks,
> > Zhengping
> >
> > On Fri, Feb 24, 2023 at 2:37 PM Zhengping Jiang <jiangzp@...gle.com> wrote:
> > >
> > > Hi Luiz,
> > >
> > > > Any particular reason why you are not using hci_cmd_sync_clear
> > > > instead?
> > >
> > > That is a good question and we used hci_cmd_sync_clear in the first
> > > version, but it will clear the queue and also close the timer. As a
> > > result, when the adapter is turned on again, the timer will not
> > > schedule any new jobs. So the option is to use hci_cmd_sync_clear and
> > > re-initiate the queue or to write a new function which only clears the
> > > queue.
> > >
> > > > We also may want to move the clearing logic to
> > > > hci_dev_close_sync since it should be equivalent to
> > > > hci_request_cancel_all.
> > >
> > > I actually have a question here. I saw
> > > "drain_workqueue(hdev->workqueue)" in hci_dev_close_sync and thought
> > > it should force clearing the cmd_sync queue. But it seems cannot
> > > prevent the use-after-free situation.
> > >
> > > Any suggestions to improve the solution?
> > >
> > > Thanks,
> > > Zhengping
> > >
> > >
> > > On Fri, Feb 24, 2023 at 1:02 PM Luiz Augusto von Dentz
> > > <luiz.dentz@...il.com> wrote:
> > > >
> > > > Hi Zhengping,
> > > >
> > > > On Fri, Feb 24, 2023 at 11:53 AM Zhengping Jiang <jiangzp@...gle.com> wrote:
> > > > >
> > > > > Clear cmd_sync_work queue before clearing the mgmt cmd list to avoid
> > > > > racing conditions which cause use-after-free.
> > > > >
> > > > > When powering off the adapter, the mgmt cmd list will be cleared. If a
> > > > > work is queued in the cmd_sync_work queue at the same time, it will
> > > > > cause the risk of use-after-free, as the cmd pointer is not checked
> > > > > before use.
> > > > >
> > > > > Signed-off-by: Zhengping Jiang <jiangzp@...gle.com>
> > > > > ---
> > > > >
> > > > > Changes in v2:
> > > > > - Add function to clear the queue without stop the timer
> > > > >
> > > > > Changes in v1:
> > > > > - Clear cmd_sync_work queue before clearing the mgmt cmd list
> > > > >
> > > > > net/bluetooth/hci_sync.c | 21 ++++++++++++++++++++-
> > > > > 1 file changed, 20 insertions(+), 1 deletion(-)
> > > > >
> > > > > diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
> > > > > index 117eedb6f709..b70365dfff0c 100644
> > > > > --- a/net/bluetooth/hci_sync.c
> > > > > +++ b/net/bluetooth/hci_sync.c
> > > > > @@ -636,6 +636,23 @@ void hci_cmd_sync_init(struct hci_dev *hdev)
> > > > > INIT_DELAYED_WORK(&hdev->adv_instance_expire, adv_timeout_expire);
> > > > > }
> > > > >
> > > > > +static void hci_pend_cmd_sync_clear(struct hci_dev *hdev)
> > > > > +{
> > > > > + struct hci_cmd_sync_work_entry *entry, *tmp;
> > > > > +
> > > > > + mutex_lock(&hdev->cmd_sync_work_lock);
> > > > > + list_for_each_entry_safe(entry, tmp, &hdev->cmd_sync_work_list, list) {
> > > > > + if (entry->destroy) {
> > > > > + hci_req_sync_lock(hdev);
> > > > > + entry->destroy(hdev, entry->data, -ECANCELED);
> > > > > + hci_req_sync_unlock(hdev);
> > > > > + }
> > > > > + list_del(&entry->list);
> > > > > + kfree(entry);
> > > > > + }
> > > > > + mutex_unlock(&hdev->cmd_sync_work_lock);
> > > > > +}
> > > > > +
> > > > > void hci_cmd_sync_clear(struct hci_dev *hdev)
> > > > > {
> > > > > struct hci_cmd_sync_work_entry *entry, *tmp;
> > > > > @@ -4842,8 +4859,10 @@ int hci_dev_close_sync(struct hci_dev *hdev)
> > > > >
> > > > > if (!auto_off && hdev->dev_type == HCI_PRIMARY &&
> > > > > !hci_dev_test_flag(hdev, HCI_USER_CHANNEL) &&
> > > > > - hci_dev_test_flag(hdev, HCI_MGMT))
> > > > > + hci_dev_test_flag(hdev, HCI_MGMT)) {
> > > > > + hci_pend_cmd_sync_clear(hdev);
> > > >
> > > > Any particular reason why you are not using hci_cmd_sync_clear
> > > > instead? We also may want to move the clearing logic to
> > > > hci_dev_close_sync since it should be equivalent to
> > > > hci_request_cancel_all.
> > > >
> > > > > __mgmt_power_off(hdev);
> > > > > + }
> > > > >
> > > > > hci_inquiry_cache_flush(hdev);
> > > > > hci_pend_le_actions_clear(hdev);
> > > > > --
> > > > > 2.39.2.722.g9855ee24e9-goog
> > > > >
> > > >
> > > >
> > > > --
> > > > Luiz Augusto von Dentz
>
>
>
> --
> Luiz Augusto von Dentz
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