ext2: ensure fast symlinks are NUL-terminated

Ensure fast symlink targets are NUL-terminated, even if corrupted
on-disk.

Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Duane Griffin <duaneg@dghda.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/ext2/inode.c

@@ -32,6 +32,7 @@
 #include <linux/buffer_head.h>
 #include <linux/mpage.h>
 #include <linux/fiemap.h>
+#include <linux/namei.h>
 #include "ext2.h"
 #include "acl.h"
 #include "xip.h"
@@ -1286,9 +1287,11 @@ struct inode *ext2_iget (struct super_block *sb, unsigned long ino)
 		else
 			inode->i_mapping->a_ops = &ext2_aops;
 	} else if (S_ISLNK(inode->i_mode)) {
-		if (ext2_inode_is_fast_symlink(inode))
+		if (ext2_inode_is_fast_symlink(inode)) {
 			inode->i_op = &ext2_fast_symlink_inode_operations;
-		else {
+			nd_terminate_link(ei->i_data, inode->i_size,
+				sizeof(ei->i_data) - 1);
+		} else {
 			inode->i_op = &ext2_symlink_inode_operations;
 			if (test_opt(inode->i_sb, NOBH))
 				inode->i_mapping->a_ops = &ext2_nobh_aops;