convert a bunch of open-coded instances of memdup_user_nul()

A _lot_ of ->write() instances were open-coding it; some are
converted to memdup_user_nul(), a lot more remain...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

3 files changed, 9 insertions, 27 deletions

diff --git a/drivers/net/wireless/ath/wil6210/debugfs.c b/drivers/net/wireless/ath/wil6210/debugfs.c
index 97bc186f9728..a1d10b85989f 100644
--- a/drivers/net/wireless/ath/wil6210/debugfs.c
+++ b/drivers/net/wireless/ath/wil6210/debugfs.c
@@ -580,16 +580,10 @@ static ssize_t wil_write_file_rxon(struct file *file, const char __user *buf,
 	long channel;
 	bool on;
 
-	char *kbuf = kmalloc(len + 1, GFP_KERNEL);
-
-	if (!kbuf)
-		return -ENOMEM;
-	if (copy_from_user(kbuf, buf, len)) {
-		kfree(kbuf);
-		return -EIO;
-	}
+	char *kbuf = memdup_user_nul(buf, len);
 
-	kbuf[len] = '\0';
+	if (IS_ERR(kbuf))
+		return PTR_ERR(kbuf);
 	rc = kstrtol(kbuf, 0, &channel);
 	kfree(kbuf);
 	if (rc)
diff --git a/drivers/s390/char/vmcp.c b/drivers/s390/char/vmcp.c
index 0fdedadff7bc..2a67b496a9e2 100644
--- a/drivers/s390/char/vmcp.c
+++ b/drivers/s390/char/vmcp.c
@@ -88,14 +88,9 @@ vmcp_write(struct file *file, const char __user *buff, size_t count,
 
 	if (count > 240)
 		return -EINVAL;
-	cmd = kmalloc(count + 1, GFP_KERNEL);
-	if (!cmd)
-		return -ENOMEM;
-	if (copy_from_user(cmd, buff, count)) {
-		kfree(cmd);
-		return -EFAULT;
-	}
-	cmd[count] = '\0';
+	cmd = memdup_user_nul(buff, count);
+	if (IS_ERR(cmd))
+		return PTR_ERR(cmd);
 	session = file->private_data;
 	if (mutex_lock_interruptible(&session->mutex)) {
 		kfree(cmd);
diff --git a/drivers/sbus/char/openprom.c b/drivers/sbus/char/openprom.c
index 5843288f64bc..e077ebd89319 100644
--- a/drivers/sbus/char/openprom.c
+++ b/drivers/sbus/char/openprom.c
@@ -390,16 +390,9 @@ static int copyin_string(char __user *user, size_t len, char **ptr)
 	if ((ssize_t)len < 0 || (ssize_t)(len + 1) < 0)
 		return -EINVAL;
 
-	tmp = kmalloc(len + 1, GFP_KERNEL);
-	if (!tmp)
-		return -ENOMEM;
-
-	if (copy_from_user(tmp, user, len)) {
-		kfree(tmp);
-		return -EFAULT;
-	}
-
-	tmp[len] = '\0';
+	tmp = memdup_user_nul(user, len);
+	if (IS_ERR(tmp))
+		return PTR_ERR(tmp);
 
 	*ptr = tmp;