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ALSA: firewire-lib: avoid NULL pointer dereference after closing MIDI port

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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 <dan.carpenter@oracle.com>
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Sakamoto 2015-10-18 22:58:37 +09:00 committed by Takashi Iwai
parent bd04809bbe
commit 56b1c72a75
1 changed files with 5 additions and 1 deletions
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6
sound/firewire/lib.c
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@ -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_fw_async_midi_port *port = callback_data;
struct snd_rawmidi_substream *substream = ACCESS_ONCE(port->substream); 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); snd_rawmidi_transmit_ack(substream, port->consume_bytes);
else if (!rcode_is_permanent_error(rcode)) else if (!rcode_is_permanent_error(rcode))
/* To start next transaction immediately for recovery. */ /* To start next transaction immediately for recovery. */