sysv: ensure fast symlinks are NUL-terminated

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

Cc: Christoph Hellwig <hch@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Duane Griffin <duaneg@dghda.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/sysv/inode.c

@@ -27,6 +27,7 @@
 #include <linux/init.h>
 #include <linux/buffer_head.h>
 #include <linux/vfs.h>
+#include <linux/namei.h>
 #include <asm/byteorder.h>
 #include "sysv.h"
 
@@ -163,8 +164,11 @@ void sysv_set_inode(struct inode *inode, dev_t rdev)
 		if (inode->i_blocks) {
 			inode->i_op = &sysv_symlink_inode_operations;
 			inode->i_mapping->a_ops = &sysv_aops;
-		} else
+		} else {
 			inode->i_op = &sysv_fast_symlink_inode_operations;
+			nd_terminate_link(SYSV_I(inode)->i_data, inode->i_size,
+				sizeof(SYSV_I(inode)->i_data) - 1);
+		}
 	} else
 		init_special_inode(inode, inode->i_mode, rdev);
 }