From ade9b5ebed44b0c15522c27669ef6cdf93eff84e Mon Sep 17 00:00:00 2001
From: Albert Astals Cid <aacid@kde.org>
Date: Tue, 17 Dec 2024 18:59:01 +0100
Subject: [PATCH] JBIG2Bitmap::combine: Fix crash on malformed files

Fixes #1553
---
 poppler/JBIG2Stream.cc | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/poppler/JBIG2Stream.cc b/poppler/JBIG2Stream.cc
index f482a123f..b2f96e149 100644
--- a/poppler/JBIG2Stream.cc
+++ b/poppler/JBIG2Stream.cc
@@ -857,7 +857,7 @@
 
 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;
@@ -902,13 +902,16 @@
   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;
@@ -931,7 +934,7 @@
 	}
 	*destPtr = dest;
       } else {
-	destPtr = data + (y + yy) * line;
+	destPtr = data + yyy * line;
 	srcPtr = bitmap->data + yy * bitmap->line + (-x >> 3);
 	dest = *destPtr;
 	src1 = *srcPtr;
@@ -961,7 +964,7 @@
 
       // 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;
@@ -985,7 +988,7 @@
 	*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;
-- 
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