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, 12 insertions, 36 deletions

diff --git a/fs/afs/proc.c b/fs/afs/proc.c
index 24a905b076fd..2853b4095344 100644
--- a/fs/afs/proc.c
+++ b/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;
 }
diff --git a/fs/cachefiles/daemon.c b/fs/cachefiles/daemon.c
index f601def05bdf..452e98dd7560 100644
--- a/fs/cachefiles/daemon.c
+++ b/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))
diff --git a/fs/dlm/user.c b/fs/dlm/user.c
index 173b3873a4f4..1925d6d222b8 100644
--- a/fs/dlm/user.c
+++ b/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;