fs/ntfs3: Deny getting attr data block in compressed frame

Attempting to retrieve an attribute data block in a compressed frame
is ignored.

Fixes: be71b5cb ("fs/ntfs3: Add attrib operations")
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>

fs/ntfs3/attrib.c

@@ -975,6 +975,19 @@ int attr_data_get_block(struct ntfs_inode *ni, CLST vcn, CLST clen, CLST *lcn,
 	if (err)
 		goto out;
 
+	/* Check for compressed frame. */
+	err = attr_is_frame_compressed(ni, attr, vcn >> NTFS_LZNT_CUNIT, &hint);
+	if (err)
+		goto out;
+
+	if (hint) {
+		/* if frame is compressed - don't touch it. */
+		*lcn = COMPRESSED_LCN;
+		*len = hint;
+		err = -EOPNOTSUPP;
+		goto out;
+	}
+
 	if (!*len) {
 		if (run_lookup_entry(run, vcn, lcn, len, NULL)) {
 			if (*lcn != SPARSE_LCN || !new)