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 <CABBYNZ+yVWssa09NB+ahp-N87sLXRqYF58-GJK-Vx8jn-Sa5Uw@mail.gmail.com>
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In-Reply-To: <CABBYNZL=u88Ro1dR8fYWpiS6E1sZ4E8TXg8BVU7nEGBodYhTrA@mail.gmail.com>
From:   Zhengping Jiang <jiangzp@google.com>
Date:   Mon, 27 Feb 2023 15:58:31 -0800
Message-ID: <CAB4PzUr9vE2m-uWVvcTa0SaeryLxhj8sZbvRqSkqLKDFwMoeyQ@mail.gmail.com>
Subject: Re: [kernel PATCH v2 1/1] Bluetooth: hci_sync: clear workqueue before
 clear mgmt cmd
To:     Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Cc:     linux-bluetooth@vger.kernel.org, marcel@holtmann.org,
        mmandlik@google.com, chromeos-bluetooth-upstreaming@chromium.org,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Johan Hedberg <johan.hedberg@gmail.com>,
        Paolo Abeni <pabeni@redhat.com>, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

Hi Luiz,

Sure. Hope this helps.
Here is one log from the user.

[   53.368740] =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
[   53.376167] BUG: KASAN: use-after-free in set_ssp_sync+0x44/0x154 [bluet=
ooth]
[   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] =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
[   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=E2=80=AFPM Luiz Augusto von Dentz
<luiz.dentz@gmail.com> wrote:
>
> Hi Zhengping,
>
> On Sun, Feb 26, 2023 at 11:18=E2=80=AFPM Zhengping Jiang <jiangzp@google.=
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=E2=80=AFPM Zhengping Jiang <jiangzp@google=
.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 th=
e
> > > 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@gmail.com> wrote:
> > > >
> > > > Hi Zhengping,
> > > >
> > > > On Fri, Feb 24, 2023 at 11:53 AM Zhengping Jiang <jiangzp@google.co=
m> wrote:
> > > > >
> > > > > Clear cmd_sync_work queue before clearing the mgmt cmd list to av=
oid
> > > > > 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 wi=
ll
> > > > > cause the risk of use-after-free, as the cmd pointer is not check=
ed
> > > > > before use.
> > > > >
> > > > > Signed-off-by: Zhengping Jiang <jiangzp@google.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, -ECANCE=
LED);
> > > > > +                       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 *hde=
v)
> > > > >
> > > > >         if (!auto_off && hdev->dev_type =3D=3D 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