netdev - Re: [PATCH v2] Bluetooth: btusb: fix memory leak on suspend and resume

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Message-Id: <B529E35E-EAB3-4D8C-B615-9D5C3BDECB94@holtmann.org>
Date:   Mon, 25 Jan 2021 19:25:41 +0100
From:   Marcel Holtmann <marcel@...tmann.org>
To:     Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@...il.com>
Cc:     Johan Hedberg <johan.hedberg@...il.com>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        "David S. Miller" <davem@...emloft.net>, kuba@...nel.org,
        linux-bluetooth@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] Bluetooth: btusb: fix memory leak on suspend and
 resume

Hi Vamshi,

> kmemleak report:
> unreferenced object 0xffff9b1127f00500 (size 208):
>  comm "kworker/u17:2", pid 500, jiffies 4294937470 (age 580.136s)
>  hex dump (first 32 bytes):
>    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>    00 60 ed 05 11 9b ff ff 00 00 00 00 00 00 00 00  .`..............
>  backtrace:
>    [<000000006ab3fd59>] kmem_cache_alloc_node+0x17a/0x480
>    [<0000000051a5f6f9>] __alloc_skb+0x5b/0x1d0
>    [<0000000037e2d252>] hci_prepare_cmd+0x32/0xc0 [bluetooth]
>    [<0000000010b586d5>] hci_req_add_ev+0x84/0xe0 [bluetooth]
>    [<00000000d2deb520>] hci_req_clear_event_filter+0x42/0x70 [bluetooth]
>    [<00000000f864bd8c>] hci_req_prepare_suspend+0x84/0x470 [bluetooth]
>    [<000000001deb2cc4>] hci_prepare_suspend+0x31/0x40 [bluetooth]
>    [<000000002677dd79>] process_one_work+0x209/0x3b0
>    [<00000000aaa62b07>] worker_thread+0x34/0x400
>    [<00000000826d176c>] kthread+0x126/0x140
>    [<000000002305e558>] ret_from_fork+0x22/0x30
> unreferenced object 0xffff9b1125c6ee00 (size 512):
>  comm "kworker/u17:2", pid 500, jiffies 4294937470 (age 580.136s)
>  hex dump (first 32 bytes):
>    04 00 00 00 0d 00 00 00 05 0c 01 00 11 9b ff ff  ................
>    00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00  ................
>  backtrace:
>    [<000000009f07c0cc>] slab_post_alloc_hook+0x59/0x270
>    [<0000000049431dc2>] __kmalloc_node_track_caller+0x15f/0x330
>    [<00000000027a42f6>] __kmalloc_reserve.isra.70+0x31/0x90
>    [<00000000e8e3e76a>] __alloc_skb+0x87/0x1d0
>    [<0000000037e2d252>] hci_prepare_cmd+0x32/0xc0 [bluetooth]
>    [<0000000010b586d5>] hci_req_add_ev+0x84/0xe0 [bluetooth]
>    [<00000000d2deb520>] hci_req_clear_event_filter+0x42/0x70 [bluetooth]
>    [<00000000f864bd8c>] hci_req_prepare_suspend+0x84/0x470 [bluetooth]
>    [<000000001deb2cc4>] hci_prepare_suspend+0x31/0x40 [bluetooth]
>    [<000000002677dd79>] process_one_work+0x209/0x3b0
>    [<00000000aaa62b07>] worker_thread+0x34/0x400
>    [<00000000826d176c>] kthread+0x126/0x140
>    [<000000002305e558>] ret_from_fork+0x22/0x30
> unreferenced object 0xffff9b112b395788 (size 8):
>  comm "kworker/u17:2", pid 500, jiffies 4294937470 (age 580.136s)
>  hex dump (first 8 bytes):
>    20 00 00 00 00 00 04 00                           .......
>  backtrace:
>    [<0000000052dc28d2>] kmem_cache_alloc_trace+0x15e/0x460
>    [<0000000046147591>] alloc_ctrl_urb+0x52/0xe0 [btusb]
>    [<00000000a2ed3e9e>] btusb_send_frame+0x91/0x100 [btusb]
>    [<000000001e66030e>] hci_send_frame+0x7e/0xf0 [bluetooth]
>    [<00000000bf6b7269>] hci_cmd_work+0xc5/0x130 [bluetooth]
>    [<000000002677dd79>] process_one_work+0x209/0x3b0
>    [<00000000aaa62b07>] worker_thread+0x34/0x400
>    [<00000000826d176c>] kthread+0x126/0x140
>    [<000000002305e558>] ret_from_fork+0x22/0x30
> 
> In pm sleep-resume context, while the btusb device rebinds, it enters
> hci_unregister_dev(), whilst there is a possibility of hdev receiving
> PM_POST_SUSPEND suspend_notifier event, leading to generation of msg
> frames. When hci_unregister_dev() completes, i.e. hdev context is
> destroyed/freed, those intermittently sent msg frames cause memory
> leak.
> 
> BUG details:
> Below is stack trace of thread that enters hci_unregister_dev(), marks
> the hdev flag HCI_UNREGISTER to 1, and then goes onto to wait on notifier
> lock - refer unregister_pm_notifier().
> 
>  hci_unregister_dev+0xa5/0x320 [bluetoot]
>  btusb_disconnect+0x68/0x150 [btusb]
>  usb_unbind_interface+0x77/0x250
>  ? kernfs_remove_by_name_ns+0x75/0xa0
>  device_release_driver_internal+0xfe/0x1
>  device_release_driver+0x12/0x20
>  bus_remove_device+0xe1/0x150
>  device_del+0x192/0x3e0
>  ? usb_remove_ep_devs+0x1f/0x30
>  usb_disable_device+0x92/0x1b0
>  usb_disconnect+0xc2/0x270
>  hub_event+0x9f6/0x15d0
>  ? rpm_idle+0x23/0x360
>  ? rpm_idle+0x26b/0x360
>  process_one_work+0x209/0x3b0
>  worker_thread+0x34/0x400
>  ? process_one_work+0x3b0/0x3b0
>  kthread+0x126/0x140
>  ? kthread_park+0x90/0x90
>  ret_from_fork+0x22/0x30
> 
> Below is stack trace of thread executing hci_suspend_notifier() which
> processes the PM_POST_SUSPEND event, while the unbinding thread is
> waiting on lock.
> 
>  hci_suspend_notifier.cold.39+0x5/0x2b [bluetooth]
>  blocking_notifier_call_chain+0x69/0x90
>  pm_notifier_call_chain+0x1a/0x20
>  pm_suspend.cold.9+0x334/0x352
>  state_store+0x84/0xf0
>  kobj_attr_store+0x12/0x20
>  sysfs_kf_write+0x3b/0x40
>  kernfs_fop_write+0xda/0x1c0
>  vfs_write+0xbb/0x250
>  ksys_write+0x61/0xe0
>  __x64_sys_write+0x1a/0x20
>  do_syscall_64+0x37/0x80
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> 
> Fix hci_suspend_notifer(), not to act on events when flag HCI_UNREGISTER
> is set.
> 
> Signed-off-by: Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@...il.com>
> ---
> net/bluetooth/hci_core.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)

patch has been applied to bluetooth-next tree.

Regards

Marcel