[PATCH 5.4 024/222] ALSA: firewire-tascam: fix corruption due to spin lock without restoration in SoftIRQ context

Greg Kroah-Hartman
2020-01-22T09:45:17Z

From: Takashi Sakamoto <o-takashi@sakamocchi.jp>

commit 747d1f076de5a60770011f6e512de43298ec64cb upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
sound/firewire/tascam/amdtp-tascam.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/sound/firewire/tascam/amdtp-tascam.c
+++ b/sound/firewire/tascam/amdtp-tascam.c
@@ -157,14 +157,15 @@ static void read_status_messages(struct
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);
}