Fix PDF infinite loop (#2128)

Port of https://github.com/zxing-cpp/zxing-cpp/pull/320

1 files changed, 2 insertions, 1 deletions

diff --git a/core/src/main/java/com/google/zxing/pdf417/detector/Detector.java b/core/src/main/java/com/google/zxing/pdf417/detector/Detector.java
index cda7f650f..6d578c672 100644
--- a/core/src/main/java/com/google/zxing/pdf417/detector/Detector.java
+++ b/core/src/main/java/com/google/zxing/pdf417/detector/Detector.java
@@ -212,11 +212,12 @@ public final class Detector {
                                                    int[] pattern) {
     ResultPoint[] result = new ResultPoint[4];
     boolean found = false;
+    int minStartRow = startRow;
     int[] counters = new int[pattern.length];
     for (; startRow < height; startRow += ROW_STEP) {
       int[] loc = findGuardPattern(matrix, startColumn, startRow, width, pattern, counters);
       if (loc != null) {
-        while (startRow > 0) {
+        while (startRow > minStartRow + 1) {
           int[] previousRowLoc = findGuardPattern(matrix, startColumn, --startRow, width, pattern, counters);
           if (previousRowLoc != null) {
             loc = previousRowLoc;