Hi,
On Tue, Jan 17, 2023 at 05:17:29PM +0300, Dan Carpenter wrote:
> 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(-)
Indeed. Thanks for your care.
Acked-by: Takashi Sakamoto <o-takashi@xxxxxxxxxxxxx>
> 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
Regards
Takashi Sakamoto
