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>

Author: Al Viro

arch/xtensa/platforms/iss/simdisk.c

@@ -227,25 +227,19 @@ static ssize_t proc_read_simdisk(struct file *file, char __user *buf,
 static ssize_t proc_write_simdisk(struct file *file, const char __user *buf,
 			size_t count, loff_t *ppos)
 {
-	char *tmp = kmalloc(count + 1, GFP_KERNEL);
+	char *tmp = memdup_user_nul(buf, count);
 	struct simdisk *dev = PDE_DATA(file_inode(file));
 	int err;
 
-	if (tmp == NULL)
-		return -ENOMEM;
-	if (copy_from_user(tmp, buf, count)) {
-		err = -EFAULT;
-		goto out_free;
-	}
+	if (IS_ERR(tmp))
+		return PTR_ERR(tmp);
 
 	err = simdisk_detach(dev);
 	if (err != 0)
 		goto out_free;
 
 	if (count > 0 && tmp[count - 1] == '\n')
 		tmp[count - 1] = 0;
-	else
-		tmp[count] = 0;
 
 	if (tmp[0])
 		err = simdisk_attach(dev, tmp);

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)

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);

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;
 

fs/afs/proc.c

@@ -230,14 +230,9 @@ static ssize_t afs_proc_cells_write(struct file *file, const char __user *buf,
 	if (size <= 1 || size >= PAGE_SIZE)
 		return -EINVAL;
 
-	kbuf = kmalloc(size + 1, GFP_KERNEL);
-	if (!kbuf)
-		return -ENOMEM;
-
-	ret = -EFAULT;
-	if (copy_from_user(kbuf, buf, size) != 0)
-		goto done;
-	kbuf[size] = 0;
+	kbuf = memdup_user_nul(buf, size);
+	if (IS_ERR(kbuf))
+		return PTR_ERR(kbuf);
 
 	/* trim to first NL */
 	name = memchr(kbuf, '\n', size);
@@ -315,15 +310,9 @@ static ssize_t afs_proc_rootcell_write(struct file *file,
 	if (size <= 1 || size >= PAGE_SIZE)
 		return -EINVAL;
 
-	ret = -ENOMEM;
-	kbuf = kmalloc(size + 1, GFP_KERNEL);
-	if (!kbuf)
-		goto nomem;
-
-	ret = -EFAULT;
-	if (copy_from_user(kbuf, buf, size) != 0)
-		goto infault;
-	kbuf[size] = 0;
+	kbuf = memdup_user_nul(buf, size);
+	if (IS_ERR(kbuf))
+		return PTR_ERR(kbuf);
 
 	/* trim to first NL */
 	s = memchr(kbuf, '\n', size);
@@ -337,9 +326,7 @@ static ssize_t afs_proc_rootcell_write(struct file *file,
 	if (ret >= 0)
 		ret = size;	/* consume everything, always */
 
-infault:
 	kfree(kbuf);
-nomem:
 	_leave(" = %d", ret);
 	return ret;
 }

fs/cachefiles/daemon.c

@@ -226,15 +226,9 @@ static ssize_t cachefiles_daemon_write(struct file *file,
 		return -EOPNOTSUPP;
 
 	/* drag the command string into the kernel so we can parse it */
-	data = kmalloc(datalen + 1, GFP_KERNEL);
-	if (!data)
-		return -ENOMEM;
-
-	ret = -EFAULT;
-	if (copy_from_user(data, _data, datalen) != 0)
-		goto error;
-
-	data[datalen] = '\0';
+	data = memdup_user_nul(_data, datalen);
+	if (IS_ERR(data))
+		return PTR_ERR(data);
 
 	ret = -EINVAL;
 	if (memchr(data, '\0', datalen))

fs/dlm/user.c

@@ -515,14 +515,9 @@ static ssize_t device_write(struct file *file, const char __user *buf,
 	if (count > sizeof(struct dlm_write_request) + DLM_RESNAME_MAXLEN)
 		return -EINVAL;
 
-	kbuf = kzalloc(count + 1, GFP_NOFS);
-	if (!kbuf)
-		return -ENOMEM;
-
-	if (copy_from_user(kbuf, buf, count)) {
-		error = -EFAULT;
-		goto out_free;
-	}
+	kbuf = memdup_user_nul(buf, count);
+	if (!IS_ERR(kbuf))
+		return PTR_ERR(kbuf);
 
 	if (check_version(kbuf)) {
 		error = -EBADE;

kernel/trace/blktrace.c

@@ -349,16 +349,10 @@ static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
 	if (count >= BLK_TN_MAX_MSG)
 		return -EINVAL;
 
-	msg = kmalloc(count + 1, GFP_KERNEL);
-	if (msg == NULL)
-		return -ENOMEM;
-
-	if (copy_from_user(msg, buffer, count)) {
-		kfree(msg);
-		return -EFAULT;
-	}
+	msg = memdup_user_nul(buffer, count);
+	if (IS_ERR(msg))
+		return PTR_ERR(msg);
 
-	msg[count] = '\0';
 	bt = filp->private_data;
 	__trace_note_message(bt, "%s", msg);
 	kfree(msg);

lib/dynamic_debug.c

@@ -657,14 +657,9 @@ static ssize_t ddebug_proc_write(struct file *file, const char __user *ubuf,
 		pr_warn("expected <%d bytes into control\n", USER_BUF_PAGE);
 		return -E2BIG;
 	}
-	tmpbuf = kmalloc(len + 1, GFP_KERNEL);
-	if (!tmpbuf)
-		return -ENOMEM;
-	if (copy_from_user(tmpbuf, ubuf, len)) {
-		kfree(tmpbuf);
-		return -EFAULT;
-	}
-	tmpbuf[len] = '\0';
+	tmpbuf = memdup_user_nul(ubuf, len);
+	if (IS_ERR(tmpbuf))
+		return PTR_ERR(tmpbuf);
 	vpr_info("read %d bytes from userspace\n", (int)len);
 
 	ret = ddebug_exec_queries(tmpbuf, NULL);

net/rxrpc/ar-key.c

@@ -896,15 +896,9 @@ int rxrpc_request_key(struct rxrpc_sock *rx, char __user *optval, int optlen)
 	if (optlen <= 0 || optlen > PAGE_SIZE - 1)
 		return -EINVAL;
 
-	description = kmalloc(optlen + 1, GFP_KERNEL);
-	if (!description)
-		return -ENOMEM;
-
-	if (copy_from_user(description, optval, optlen)) {
-		kfree(description);
-		return -EFAULT;
-	}
-	description[optlen] = 0;
+	description = memdup_user_nul(optval, optlen);
+	if (IS_ERR(description))
+		return PTR_ERR(description);
 
 	key = request_key(&key_type_rxrpc, description, NULL);
 	if (IS_ERR(key)) {
@@ -933,15 +927,9 @@ int rxrpc_server_keyring(struct rxrpc_sock *rx, char __user *optval,
 	if (optlen <= 0 || optlen > PAGE_SIZE - 1)
 		return -EINVAL;
 
-	description = kmalloc(optlen + 1, GFP_KERNEL);
-	if (!description)
-		return -ENOMEM;
-
-	if (copy_from_user(description, optval, optlen)) {
-		kfree(description);
-		return -EFAULT;
-	}
-	description[optlen] = 0;
+	description = memdup_user_nul(optval, optlen);
+	if (IS_ERR(description))
+		return PTR_ERR(description);
 
 	key = request_key(&key_type_keyring, description, NULL);
 	if (IS_ERR(key)) {