ALSA: firewire-tascam: fix corruption due to spin lock without restoration in SoftIRQ...

ALSA firewire-tascam driver can bring corruption due to spin lock without
restoration of IRQ flag in SoftIRQ context. This commit fixes the bug.

Cc: Scott Bahling <sbahling@suse.com>
Cc: <stable@vger.kernel.org> # v4.21
Fixes: d7167422433c ("ALSA: firewire-tascam: queue events for change of control surface")
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20200113085719.26788-1-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/firewire/tascam/amdtp-tascam.c b/sound/firewire/tascam/amdtp-tascam.c
index e80bb84..f823a2a 100644 (file)
--- a/sound/firewire/tascam/amdtp-tascam.c
+++ b/sound/firewire/tascam/amdtp-tascam.c
@@ -157,14 +157,15 @@ static void read_status_messages(struct amdtp_stream *s,
                        if ((before ^ after) & mask) {
                                struct snd_firewire_tascam_change *entry =
                                                &tscm->queue[tscm->push_pos];
+                               unsigned long flag;
 
-                               spin_lock_irq(&tscm->lock);
+                               spin_lock_irqsave(&tscm->lock, flag);
                                entry->index = index;
                                entry->before = before;
                                entry->after = after;
                                if (++tscm->push_pos >= SND_TSCM_QUEUE_COUNT)
                                        tscm->push_pos = 0;
-                               spin_unlock_irq(&tscm->lock);
+                               spin_unlock_irqrestore(&tscm->lock, flag);
 
                                wake_up(&tscm->hwdep_wait);
                        }