debugfs: make sure we can remove u32_array files cleanly

debugfs_create_u32_array() allocates a small structure to wrap
the data and size information about the array. If users ever
try to remove the file this leads to a leak since nothing ever
frees this wrapper.

That said there are no upstream users of debugfs_create_u32_array()
that'd remove a u32 array file (we only have one u32 array user in
CMA), so there is no real bug here.

Make callers pass a wrapper they allocated. This way the lifetime
management of the wrapper is on the caller, and we can avoid the
potential leak in debugfs.

CC: Chucheng Luo <luochucheng@vivo.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 20 deletions

diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index ae49a55bda00..d0ed71f37511 100644
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -918,11 +918,6 @@ struct dentry *debugfs_create_blob(const char *name, umode_t mode,
 }
 EXPORT_SYMBOL_GPL(debugfs_create_blob);
 
-struct array_data {
-	void *array;
-	u32 elements;
-};
-
 static size_t u32_format_array(char *buf, size_t bufsize,
 			       u32 *array, int array_size)
 {
@@ -943,8 +938,8 @@ static size_t u32_format_array(char *buf, size_t bufsize,
 
 static int u32_array_open(struct inode *inode, struct file *file)
 {
-	struct array_data *data = inode->i_private;
-	int size, elements = data->elements;
+	struct debugfs_u32_array *data = inode->i_private;
+	int size, elements = data->n_elements;
 	char *buf;
 
 	/*
@@ -959,7 +954,7 @@ static int u32_array_open(struct inode *inode, struct file *file)
 	buf[size] = 0;
 
 	file->private_data = buf;
-	u32_format_array(buf, size, data->array, data->elements);
+	u32_format_array(buf, size, data->array, data->n_elements);
 
 	return nonseekable_open(inode, file);
 }
@@ -996,8 +991,7 @@ static const struct file_operations u32_array_fops = {
  * @parent: a pointer to the parent dentry for this file.  This should be a
  *          directory dentry if set.  If this parameter is %NULL, then the
  *          file will be created in the root of the debugfs filesystem.
- * @array: u32 array that provides data.
- * @elements: total number of elements in the array.
+ * @array: wrapper struct containing data pointer and size of the array.
  *
  * This function creates a file in debugfs with the given name that exports
  * @array as data. If the @mode variable is so set it can be read from.
@@ -1005,17 +999,10 @@ static const struct file_operations u32_array_fops = {
  * Once array is created its size can not be changed.
  */
 void debugfs_create_u32_array(const char *name, umode_t mode,
-			      struct dentry *parent, u32 *array, u32 elements)
+			      struct dentry *parent,
+			      struct debugfs_u32_array *array)
 {
-	struct array_data *data = kmalloc(sizeof(*data), GFP_KERNEL);
-
-	if (data == NULL)
-		return;
-
-	data->array = array;
-	data->elements = elements;
-
-	debugfs_create_file_unsafe(name, mode, parent, data, &u32_array_fops);
+	debugfs_create_file_unsafe(name, mode, parent, array, &u32_array_fops);
 }
 EXPORT_SYMBOL_GPL(debugfs_create_u32_array);