Merge pull request github#4677 from jbj/largeVariable-overflow

calumgrant · web-flow · commit 9897a81a5c9d · 2020-12-01T11:54:17.000Z
C++: Decrease largeVariable cut-off to 100k
diff --git a/cpp/ql/src/semmle/code/cpp/dataflow/internal/FlowVar.qll b/cpp/ql/src/semmle/code/cpp/dataflow/internal/FlowVar.qll
@@ -620,7 +620,8 @@ module FlowVar_internal {
   private predicate largeVariable(Variable v, int liveBlocks, int defs) {
     liveBlocks = strictcount(SubBasicBlock sbb | variableLiveInSBB(sbb, v)) and
     defs = strictcount(SubBasicBlock sbb | exists(TBlockVar(sbb, v))) and
-    liveBlocks * defs > 1000000
+    // Convert to float to avoid int overflow (32-bit two's complement)
+    liveBlocks.(float) * defs.(float) > 100000.0
   }
 
   /**

Original file line number	Diff line number	Diff line change
`@@ -620,7 +620,8 @@ module FlowVar_internal {`
`620`	`620`	`private predicate largeVariable(Variable v, int liveBlocks, int defs) {`
`621`	`621`	`liveBlocks = strictcount(SubBasicBlock sbb \| variableLiveInSBB(sbb, v)) and`
`622`	`622`	`defs = strictcount(SubBasicBlock sbb \| exists(TBlockVar(sbb, v))) and`
`623`		`- liveBlocks * defs > 1000000`
	`623`	`+ // Convert to float to avoid int overflow (32-bit two's complement)`
	`624`	`+ liveBlocks.(float) * defs.(float) > 100000.0`
`624`	`625`	`}`
`625`	`626`
`626`	`627`	`/**`