Index: poppler-24.12.0/poppler/JBIG2Stream.cc
===================================================================
--- poppler-24.12.0.orig/poppler/JBIG2Stream.cc
+++ poppler-24.12.0/poppler/JBIG2Stream.cc
@@ -766,7 +766,7 @@ void JBIG2Bitmap::duplicateRow(int yDest
 
 void JBIG2Bitmap::combine(JBIG2Bitmap *bitmap, int x, int y, unsigned int combOp)
 {
-    int x0, x1, y0, y1, xx, yy;
+    int x0, x1, y0, y1, xx, yy, yyy;
     unsigned char *srcPtr, *destPtr;
     unsigned int src0, src1, src, dest, s1, s2, m1, m2, m3;
     bool oneByte;
@@ -813,14 +813,17 @@ void JBIG2Bitmap::combine(JBIG2Bitmap *b
     oneByte = x0 == ((x1 - 1) & ~7);
 
     for (yy = y0; yy < y1; ++yy) {
-        if (unlikely((y + yy >= h) || (y + yy < 0))) {
+        if (unlikely(checkedAdd(y, yy, &yyy))) {
+            continue;
+        }
+        if (unlikely((yyy >= h) || (yyy < 0))) {
             continue;
         }
 
         // one byte per line -- need to mask both left and right side
         if (oneByte) {
             if (x >= 0) {
-                destPtr = data + (y + yy) * line + (x >> 3);
+                destPtr = data + yyy * line + (x >> 3);
                 srcPtr = bitmap->data + yy * bitmap->line;
                 dest = *destPtr;
                 src1 = *srcPtr;
@@ -843,7 +846,7 @@ void JBIG2Bitmap::combine(JBIG2Bitmap *b
                 }
                 *destPtr = dest;
             } else {
-                destPtr = data + (y + yy) * line;
+                destPtr = data + yyy * line;
                 srcPtr = bitmap->data + yy * bitmap->line + (-x >> 3);
                 dest = *destPtr;
                 src1 = *srcPtr;
@@ -873,7 +876,7 @@ void JBIG2Bitmap::combine(JBIG2Bitmap *b
 
             // left-most byte
             if (x >= 0) {
-                destPtr = data + (y + yy) * line + (x >> 3);
+                destPtr = data + yyy * line + (x >> 3);
                 srcPtr = bitmap->data + yy * bitmap->line;
                 src1 = *srcPtr++;
                 dest = *destPtr;
@@ -897,7 +900,7 @@ void JBIG2Bitmap::combine(JBIG2Bitmap *b
                 *destPtr++ = dest;
                 xx = x0 + 8;
             } else {
-                destPtr = data + (y + yy) * line;
+                destPtr = data + yyy * line;
                 srcPtr = bitmap->data + yy * bitmap->line + (-x >> 3);
                 src1 = *srcPtr++;
                 xx = x0;