[pulseaudio-discuss] [PATCH] bluetooth: Fix crash when disabling Bluetooth adapter

[Tanu Kaskinen]

On Wed, 2019-06-19 at 11:09 +0200, Frédéric Danis wrote:
> This crash occurs when PA is connected to a phone through the oFono
> backend.
> When disabling the Bluetooth adapter, pa_bluetooth_device is removed before
> hf_audio_card. Both keep refs on pa_bluetooth_transport. Those removal will
> call pa_bluetooth_transport_free() from device_free() (bluez5-util.c) and
> hf_audio_card_free() (backend-ofono.c).
> In the end, the call to pa_bluetooth_transport_free() calls
> pa_hasmap_remove() through pa_bluetooth_transport_unlink(), but since
> memory has already been freed, the second try results in a segfault.
> 
> Triggering hf_audio_card removal during pa_bluetooth_device removal allows
> hf_audio_card to be freed at the right time.
> ---
>  src/modules/bluetooth/backend-ofono.c | 18 ++++++++++++++++++
>  src/modules/bluetooth/bluez5-util.c   |  2 ++
>  src/modules/bluetooth/bluez5-util.h   |  1 +
>  3 files changed, 21 insertions(+)
> 
> diff --git a/src/modules/bluetooth/backend-ofono.c b/src/modules/bluetooth/backend-ofono.c
> index 1f0efe923..0e5bbe8b7 100644
> --- a/src/modules/bluetooth/backend-ofono.c
> +++ b/src/modules/bluetooth/backend-ofono.c
> @@ -70,6 +70,7 @@ struct hf_audio_card {
>      int (*acquire)(struct hf_audio_card *card);
>  
>      pa_bluetooth_transport *transport;
> +    pa_hook_slot *device_unlink_slot;
>  };
>  
>  struct pa_bluetooth_backend {
> @@ -181,6 +182,17 @@ static int card_acquire(struct hf_audio_card *card) {
>      return -1;
>  }
>  
> +static void hf_audio_agent_card_removed(pa_bluetooth_backend *backend, const char *path);
> +
> +static pa_hook_result_t device_unlink_cb(pa_bluetooth_discovery *y, const pa_bluetooth_device *d, struct hf_audio_card *card) {
> +    pa_assert(d);
> +    pa_assert(card);
> +
> +    hf_audio_agent_card_removed(card->backend, card->path);
> +
> +    return PA_HOOK_OK;
> +}
> +
>  static struct hf_audio_card *hf_audio_card_new(pa_bluetooth_backend *backend, const char *path) {
>      struct hf_audio_card *card = pa_xnew0(struct hf_audio_card, 1);
>  
> @@ -189,12 +201,18 @@ static struct hf_audio_card *hf_audio_card_new(pa_bluetooth_backend *backend, co
>      card->fd = -1;
>      card->acquire = card_acquire;
>  
> +    card->device_unlink_slot = pa_hook_connect(pa_bluetooth_discovery_hook(backend->discovery, PA_BLUETOOTH_HOOK_DEVICE_UNLINK),
> +                                               PA_HOOK_NORMAL, (pa_hook_cb_t) device_unlink_cb, card);
> +
>      return card;
>  }
>  
>  static void hf_audio_card_free(struct hf_audio_card *card) {
>      pa_assert(card);
>  
> +    if (card->device_unlink_slot)
> +        pa_hook_slot_free(card->device_unlink_slot);
> +
>      if (card->transport)
>          pa_bluetooth_transport_free(card->transport);
>  
> diff --git a/src/modules/bluetooth/bluez5-util.c b/src/modules/bluetooth/bluez5-util.c
> index 3c5a000c0..d95c9c117 100644
> --- a/src/modules/bluetooth/bluez5-util.c
> +++ b/src/modules/bluetooth/bluez5-util.c
> @@ -562,6 +562,8 @@ static void device_free(pa_bluetooth_device *d) {
>  
>      device_stop_waiting_for_profiles(d);
>  
> +    pa_hook_fire(&d->discovery->hooks[PA_BLUETOOTH_HOOK_DEVICE_UNLINK], d);
> +
>      for (i = 0; i < PA_BLUETOOTH_PROFILE_COUNT; i++) {
>          pa_bluetooth_transport *t;
>  
> diff --git a/src/modules/bluetooth/bluez5-util.h b/src/modules/bluetooth/bluez5-util.h
> index 82739bffd..1e9caecb4 100644
> --- a/src/modules/bluetooth/bluez5-util.h
> +++ b/src/modules/bluetooth/bluez5-util.h
> @@ -50,6 +50,7 @@ typedef enum pa_bluetooth_hook {
>      PA_BLUETOOTH_HOOK_TRANSPORT_STATE_CHANGED,            /* Call data: pa_bluetooth_transport */
>      PA_BLUETOOTH_HOOK_TRANSPORT_MICROPHONE_GAIN_CHANGED,  /* Call data: pa_bluetooth_transport */
>      PA_BLUETOOTH_HOOK_TRANSPORT_SPEAKER_GAIN_CHANGED,     /* Call data: pa_bluetooth_transport */
> +    PA_BLUETOOTH_HOOK_DEVICE_UNLINK,                      /* Call data: pa_bluetooth_device */
>      PA_BLUETOOTH_HOOK_MAX
>  } pa_bluetooth_hook_t;
>  

Thanks! Applied.

-- 
Tanu

https://www.patreon.com/tanuk
https://liberapay.com/tanuk