[PATCH 2/2] misc: nsm: do not unlock mutex before locking it

[Vu Nguyen Anh Khoa]

nsm_dev_ioctl() jumps to the common out label when the initial
copy_from_user() fails. That failure path runs before
mutex_lock(&nsm->lock), but the out label unconditionally calls
mutex_unlock(&nsm->lock).

Return -EFAULT directly for the pre-lock copy_from_user() failure so
only paths that acquired the mutex release it.

Signed-off-by: Vu Nguyen Anh Khoa <khoavna.tin.2225@xxxxxxxxx>
---
 drivers/misc/nsm.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/misc/nsm.c b/drivers/misc/nsm.c
index 52790df7d..8153edff3 100644
--- a/drivers/misc/nsm.c
+++ b/drivers/misc/nsm.c
@@ -369,9 +369,8 @@ static long nsm_dev_ioctl(struct file *file, unsigned int cmd,
 		return -EINVAL;
 
 	/* Copy user argument struct to kernel argument struct */
-	r = -EFAULT;
 	if (copy_from_user(&raw, argp, _IOC_SIZE(cmd)))
-		goto out;
+		return -EFAULT;
 
 	mutex_lock(&nsm->lock);
 
-- 
2.43.0