fs/ntfs3: fix panic about slab-out-of-bounds caused by ntfs_list_ea()

Here is a BUG report about linux-6.1 from syzbot, but it still remains
within upstream:

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:
 kasan_report+0x139/0x170 mm/kasan/report.c:495
 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
 path_listxattr fs/xattr.c:828 [inline]
 __do_sys_llistxattr fs/xattr.c:846 [inline]

Before derefering field members of `ea` in unpacked_ea_size(), we need to
check whether the EA_FULL struct is located in access validate range.

Similarly, when derefering `ea->name` field member, we need to check
whethe the ea->name is located in access validate range, too.

Fixes: be71b5c ("fs/ntfs3: Add attrib operations")
Reported-by: [email protected]
Signed-off-by: Zeng Heng <[email protected]>
[[email protected]: took the ret variable out of the loop block]
Signed-off-by: Konstantin Komarov <[email protected]>

Author: henryZe

fs/ntfs3/xattr.c

@@ -211,14 +211,19 @@ static ssize_t ntfs_list_ea(struct ntfs_inode *ni, char *buffer,
 	size = le32_to_cpu(info->size);
 
 	/* Enumerate all xattrs. */
-	for (ret = 0, off = 0; off < size; off += ea_size) {
+	ret = 0;
+	for (off = 0; off + sizeof(struct EA_FULL) < size; off += ea_size) {
 		ea = Add2Ptr(ea_all, off);
 		ea_size = unpacked_ea_size(ea);
 
 		if (!ea->name_len)
 			break;
 
 		if (buffer) {
+			/* Check if we can use field ea->name */
+			if (off + ea_size > size)
+				break;
+
 			if (ret + ea->name_len + 1 > bytes_per_buffer) {
 				err = -ERANGE;
 				goto out;