configfs: Return -EFBIG from configfs_write_bin_file.

The check for writing more than cb_max_size bytes does not 'goto out' so
it is a no-op which allows users to vmalloc an arbitrary amount.

Fixes: 03607ace807b ("configfs: implement binary attributes")
Cc: stable@kernel.org
Signed-off-by: Phil Turnbull <phil.turnbull@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
diff --git a/fs/configfs/file.c b/fs/configfs/file.c
index c30cf49..2c6312d 100644
--- a/fs/configfs/file.c
+++ b/fs/configfs/file.c
@@ -333,6 +333,7 @@
 		if (bin_attr->cb_max_size &&
 			*ppos + count > bin_attr->cb_max_size) {
 			len = -EFBIG;
+			goto out;
 		}
 
 		tbuf = vmalloc(*ppos + count);