[pulseaudio-discuss] [PATCH v2] bluetooth: Fix crash in setup_stream()

[Tanu Kaskinen]

On Tue, 2019-06-18 at 10:15 +0200, Frédéric Danis wrote:
> setup_stream() crashes when calling set_nonblock() with an invalid
> stream_fd.
> 
> On a new call, the ofono backend gets notified of a new connection.
> The ofono backend sets the transport state to playing, and that triggers
> a profile change, which sets up the stream for the first time.
> Then module-bluetooth-policy sets up the loopbacks. The loopbacks get
> fully initialized before the crash.
> 
> After module-bluetooth-policy has done its things, the execution
> continues in the transport state change hook. The next hook user is
> module-bluez5-device, whose handle_transport_state_change() function
> gets called. It will then set up the stream again even though it's
> already set up. I'm not sure if that's a some kind of a bug.
> setup_stream() can handle the case where it's unnecessarily called,
> though, so this second setup is not a big problem.
> 
> The crash happens, because the connection died due to POLLHUP in the IO
> thread before the second setup_stream() call.
> ---
> Changes in v2:
> * Update comments and commit message
> 
>  src/modules/bluetooth/module-bluez5-device.c | 26 ++++++++++++++++++--
>  1 file changed, 24 insertions(+), 2 deletions(-)
> 
> diff --git a/src/modules/bluetooth/module-bluez5-device.c b/src/modules/bluetooth/module-bluez5-device.c
> index 56c96054d..91c678223 100644
> --- a/src/modules/bluetooth/module-bluez5-device.c
> +++ b/src/modules/bluetooth/module-bluez5-device.c
> @@ -753,6 +753,8 @@ static void setup_stream(struct userdata *u) {
>      struct pollfd *pollfd;
>      int one;
>  
> +    pa_assert(u->stream_fd >= 0);
> +
>      /* return if stream is already set up */
>      if (u->stream_setup_done)
>          return;
> @@ -829,7 +831,17 @@ static int source_process_msg(pa_msgobject *o, int code, void *data, int64_t off
>          }
>  
>          case PA_SOURCE_MESSAGE_SETUP_STREAM:
> -            setup_stream(u);
> +            /* Skip stream setup if stream_fd has been invalidated.
> +               This can occur if the stream has already been set up and
> +               then immediately received POLLHUP. If the stream has
> +               already been set up earlier, then this setup_stream()
> +               call is redundant anyway, but currently the code
> +               is such that this kind of unnecessary setup_stream()
> +               calls can happen. */
> +            if (u->stream_fd < 0)
> +                pa_log_debug("Skip source stream setup while closing");
> +            else
> +                setup_stream(u);
>              return 0;
>  
>      }
> @@ -1007,7 +1019,17 @@ static int sink_process_msg(pa_msgobject *o, int code, void *data, int64_t offse
>          }
>  
>          case PA_SINK_MESSAGE_SETUP_STREAM:
> -            setup_stream(u);
> +            /* Skip stream setup if stream_fd has been invalidated.
> +               This can occur if the stream has already been set up and
> +               then immediately received POLLHUP. If the stream has
> +               already been set up earlier, then this setup_stream()
> +               call is redundant anyway, but currently the code
> +               is such that this kind of unnecessary setup_stream()
> +               calls can happen. */
> +            if (u->stream_fd < 0)
> +                pa_log_debug("Skip sink stream setup while closing");
> +            else
> +                setup_stream(u);
>              return 0;
>      }
>  

Thanks! Applied.

-- 
Tanu

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