[PATCH] ALSA: fireface: fix locking bug in ff400_copy_msg_to_user()
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@gmail.com --- 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;
Hi,
On Tue, Jan 17, 2023 at 05:17:29PM +0300, Dan Carpenter wrote:
Indeed. Thanks for your care.
Acked-by: Takashi Sakamoto o-takashi@sakamocchi.jp
Regards
Takashi Sakamoto
participants (3)
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Dan Carpenter
-
Takashi Iwai
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Takashi Sakamoto