BZ 69762 - enhance

consider the possibility of integer overflow before result add.

Author: Chenjp

java/org/apache/coyote/http2/Hpack.java

@@ -179,7 +179,7 @@ static int decodeInteger(ByteBuffer source, int n) throws HpackException {
                     return -1;
                 }
                 b = source.get();
-                result = result + (b & 127) * (PREFIX_TABLE[m] + 1);
+                result = result + (b & 127) * (PREFIX_TABLE[m] + 1L);
                 if (result > Integer.MAX_VALUE) {
                     throw new HpackException(sm.getString("hpack.integerEncodedTooBig"));
                 }

test/org/apache/coyote/http2/TestHpack.java

@@ -178,6 +178,19 @@ public void testDecodeIntegerMaxValuePlus1() throws HpackException {
         Hpack.decodeInteger(bb, 1);
     }
 
+    @Test(expected = HpackException.class)
+    public void testDecodeIntegerOverflow() throws HpackException {
+        ByteBuffer bb = ByteBuffer.allocate(9);
+        bb.put((byte) 255);
+        bb.put((byte) 254);
+        bb.put((byte) 255);
+        bb.put((byte) 255);
+        bb.put((byte) 255);
+        bb.put((byte) 15);
+        bb.position(0);
+
+        Hpack.decodeInteger(bb, 1);
+    }
 
     @Test(expected = HpackException.class)
     public void testDecodeIntegerZeroValues() throws HpackException {