[OMPT-svn-commit] OpenMPT r22230 - trunk/OpenMPT/soundlib

[<sv...@op...>]

Author: sagamusix
Date: Mon Nov 18 22:35:52 2024
New Revision: 22230
URL: https://source.openmpt.org/browse/openmpt/?op=revision&rev=22230

Log:
[Fix] Avoid integer wraparound when period + fractional period exceeds 32-bit integer limits. Found with afl++ + ubsan.

Modified:
   trunk/OpenMPT/soundlib/Sndmix.cpp

Modified: trunk/OpenMPT/soundlib/Sndmix.cpp
==============================================================================
--- trunk/OpenMPT/soundlib/Sndmix.cpp	Mon Nov 18 22:27:12 2024	(r22229)
+++ trunk/OpenMPT/soundlib/Sndmix.cpp	Mon Nov 18 22:35:52 2024	(r22230)
@@ -1839,8 +1839,15 @@
 					vdelta += Util::muldiv(period, fineUpTable[l & 0x03], 0x10000) - period;
 				}
 			}
-			period = (period + vdelta) / 256;
-			nPeriodFrac = vdelta & 0xFF;
+			if(Util::MaxValueOfType(period) - period >= vdelta)
+			{
+				period = (period + vdelta) / 256;
+				nPeriodFrac = vdelta & 0xFF;
+			} else
+			{
+				period = Util::MaxValueOfType(period) / 256;
+				nPeriodFrac = 0;
+			}
 		} else
 		{
 			// MPT's autovibrato code