ntfs: Fix panic about slab-out-of-bounds caused by ntfs_listxattr()

In the Linux kernel, the following vulnerability has been resolved:

ntfs: Fix panic about slab-out-of-bounds caused by ntfs_listxattr()

Here is a BUG report from syzbot:

BUG: KASAN: slab-out-of-bounds in ntfs_list_ea fs/ntfs3/xattr.c:191 [inline] BUG: KASAN: slab-out-of-bounds in ntfs_listxattr+0x401/0x570 fs/ntfs3/xattr.c:710 Read of size 1 at addr ffff888021acaf3d by task syz-executor128/3632

Call Trace: ntfs_list_ea fs/ntfs3/xattr.c:191 [inline] ntfs_listxattr+0x401/0x570 fs/ntfs3/xattr.c:710 vfs_listxattr fs/xattr.c:457 [inline] listxattr+0x293/0x2d0 fs/xattr.c:804

Fix the logic of ea_all iteration. When the ea->name_len is 0, return immediately, or Add2Ptr() would visit invalid memory in the next loop.

[almaz.alexandrovich@paragon-software.com: lines of the patch have changed]