The ff400_copy_msg_to_user() function drops the spin lock to call
copy_to_user(). However, if the copy_to_user() fails, then it must
take the lock again before returning. Failure to take the lock leads
to a double unlock in the caller, hwdep_read().
Fixes: acdebd8b4c0c ("ALSA: fireface: implement message parser for Fireface 400")
Signed-off-by: Dan Carpenter <error27@xxxxxxxxx>
---
sound/firewire/fireface/ff-protocol-former.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/sound/firewire/fireface/ff-protocol-former.c b/sound/firewire/fireface/ff-protocol-former.c
index f58008762fe6..fa41de978756 100644
--- a/sound/firewire/fireface/ff-protocol-former.c
+++ b/sound/firewire/fireface/ff-protocol-former.c
@@ -680,28 +680,30 @@ static long ff400_copy_msg_to_user(struct snd_ff *ff, char __user *buf, long cou
struct ff400_msg_parser *parser = ff->msg_parser;
u32 type = SNDRV_FIREWIRE_EVENT_FF400_MESSAGE;
long consumed = 0;
+ int ret = 0;
if (count < 8)
return 0;
spin_unlock_irq(&ff->lock);
-
if (copy_to_user(buf, &type, sizeof(type)))
- return -EFAULT;
-
+ ret = -EFAULT;
spin_lock_irq(&ff->lock);
+ if (ret)
+ return ret;
count -= sizeof(type);
consumed += sizeof(type);
while (count >= sizeof(*parser->msgs) && parser->pull_pos != parser->push_pos) {
spin_unlock_irq(&ff->lock);
-
if (copy_to_user(buf + consumed, parser->msgs + parser->pull_pos,
sizeof(*parser->msgs)))
- return -EFAULT;
-
+ ret = -EFAULT;
spin_lock_irq(&ff->lock);
+ if (ret)
+ return ret;
+
++parser->pull_pos;
if (parser->pull_pos >= FF400_QUEUE_SIZE)
parser->pull_pos = 0;
--
2.35.1
