From 56b1c72a75ec44a98aca8bbd71ac869a6f54e036 Mon Sep 17 00:00:00 2001 From: Takashi Sakamoto Date: Sun, 18 Oct 2015 22:58:37 +0900 Subject: [PATCH 60/63] ALSA: firewire-lib: avoid NULL pointer dereference after closing MIDI port When asynchronous MIDI port is closed before callbacked, the callback function causes NULL pointer dereference to missing MIDI substream. This commit fixes this bug. Fixes: e8a40d9bcb23('ALSA: firewire-lib: schedule work again when MIDI substream has rest of MIDI messages') Reported-by: Dan Carpenter Signed-off-by: Takashi Sakamoto Signed-off-by: Takashi Iwai --- sound/firewire/lib.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/sound/firewire/lib.c b/sound/firewire/lib.c index edf1c8bd25a6..f80aafa44c89 100644 --- a/sound/firewire/lib.c +++ b/sound/firewire/lib.c @@ -74,7 +74,11 @@ static void async_midi_port_callback(struct fw_card *card, int rcode, struct snd_fw_async_midi_port *port = callback_data; struct snd_rawmidi_substream *substream = ACCESS_ONCE(port->substream); - if (rcode == RCODE_COMPLETE && substream != NULL) + /* This port is closed. */ + if (substream == NULL) + return; + + if (rcode == RCODE_COMPLETE) snd_rawmidi_transmit_ack(substream, port->consume_bytes); else if (!rcode_is_permanent_error(rcode)) /* To start next transaction immediately for recovery. */ -- 2.4.10