[OMPT-svn-commit] OpenMPT r22357 - trunk/OpenMPT/soundlib

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

Author: sagamusix
Date: Sat Nov 30 16:52:35 2024
New Revision: 22357
URL: https://source.openmpt.org/browse/openmpt/?op=revision&rev=22357

Log:
[Fix] Avoid undefined behaviour when writing past end of span (it was guaranteed to be a valid write, but still UB according to span API contract).

Modified:
   trunk/OpenMPT/soundlib/Snd_fx.cpp

Modified: trunk/OpenMPT/soundlib/Snd_fx.cpp
==============================================================================
--- trunk/OpenMPT/soundlib/Snd_fx.cpp	Sat Nov 30 14:50:41 2024	(r22356)
+++ trunk/OpenMPT/soundlib/Snd_fx.cpp	Sat Nov 30 16:52:35 2024	(r22357)
@@ -5436,6 +5436,7 @@
 			} else
 			{
 				// SysEx message, find end of message
+				sendLen = outSize - sendPos;
 				for(uint32 i = sendPos + 1; i < outSize; i++)
 				{
 					if(out[i] == 0xF7)
@@ -5445,12 +5446,6 @@
 						break;
 					}
 				}
-				if(sendLen == 0)
-				{
-					// Didn't find end, so "invent" end of SysEx message
-					out[outSize++] = 0xF7;
-					sendLen = outSize - sendPos;
-				}
 			}
 		} else if(!(out[sendPos] & 0x80))
 		{
@@ -5658,14 +5653,32 @@
 			firstNibble = true;
 		}
 	}
+	// Finish current byte
 	if(!firstNibble)
-	{
-		// Finish current byte
 		outPos++;
-	}
 	if(updateZxxParam < 0x80)
 		chn.lastZxxParam = updateZxxParam;
 
+	// Add end of SysEx byte if necessary
+	for(size_t i = 0; i < outPos; i++)
+	{
+		if(out[i] != 0xF0)
+			continue;
+		if(outPos - i >= 4 && (out[i + 1] == 0xF0 || out[i + 1] == 0xF1))
+		{
+			// Internal message
+			i += 3;
+		} else
+		{
+			// Real SysEx
+			while(i < outPos && out[i] != 0xF7)
+				i++;
+			if(i == outPos && outPos < out.size())
+				out[outPos++] = 0xF7;
+		}
+		
+	}
+
 	out = out.first(outPos);
 }