C++: Expose a public memset model and use it in the exposure queries.

Author: MathiasVP

cpp/ql/lib/semmle/code/cpp/models/implementations/Memset.qll

@@ -9,18 +9,17 @@ import semmle.code.cpp.models.interfaces.DataFlow
 import semmle.code.cpp.models.interfaces.Alias
 import semmle.code.cpp.models.interfaces.SideEffect
 
-/**
- * The standard function `memset` and its assorted variants
- */
-private class MemsetFunction extends ArrayFunction, DataFlowFunction, AliasFunction,
+private class MemsetFunctionModel extends ArrayFunction, DataFlowFunction, AliasFunction,
   SideEffectFunction
 {
-  MemsetFunction() {
+  MemsetFunctionModel() {
     this.hasGlobalOrStdOrBslName("memset")
     or
     this.hasGlobalOrStdName("wmemset")
     or
-    this.hasGlobalName([bzero(), "__builtin_memset", "__builtin_memset_chk"])
+    this.hasGlobalName([
+        bzero(), "__builtin_memset", "__builtin_memset_chk", "RtlZeroMemory", "RtlSecureZeroMemory"
+      ])
   }
 
   override predicate hasArrayOutput(int bufParam) { bufParam = 0 }
@@ -60,3 +59,8 @@ private class MemsetFunction extends ArrayFunction, DataFlowFunction, AliasFunct
 }
 
 private string bzero() { result = ["bzero", "explicit_bzero"] }
+
+/**
+ * The standard function `memset` and its assorted variants
+ */
+class MemsetFunction extends Function instanceof MemsetFunctionModel { }

cpp/ql/src/Security/CWE/CWE-497/ExposedSystemData.ql

@@ -15,6 +15,7 @@
 import cpp
 import semmle.code.cpp.ir.dataflow.TaintTracking
 import semmle.code.cpp.models.interfaces.FlowSource
+import semmle.code.cpp.models.implementations.Memset
 import ExposedSystemData::PathGraph
 import SystemData
 
@@ -28,6 +29,10 @@ module ExposedSystemDataConfig implements DataFlow::ConfigSig {
       fc.getArgument(arg).getAChild*() = sink.asIndirectExpr()
     )
   }
+
+  predicate isBarrier(DataFlow::Node node) {
+    node.asIndirectArgument() = any(MemsetFunction func).getACallToThisFunction().getAnArgument()
+  }
 }
 
 module ExposedSystemData = TaintTracking::Global<ExposedSystemDataConfig>;

cpp/ql/src/Security/CWE/CWE-497/PotentiallyExposedSystemData.ql

@@ -28,6 +28,7 @@ import cpp
 import semmle.code.cpp.ir.dataflow.TaintTracking
 import semmle.code.cpp.models.interfaces.FlowSource
 import semmle.code.cpp.security.OutputWrite
+import semmle.code.cpp.models.implementations.Memset
 import PotentiallyExposedSystemData::PathGraph
 import SystemData
 
@@ -49,6 +50,10 @@ module PotentiallyExposedSystemDataConfig implements DataFlow::ConfigSig {
       else child = sink.asExpr()
     )
   }
+
+  predicate isBarrier(DataFlow::Node node) {
+    node.asIndirectArgument() = any(MemsetFunction func).getACallToThisFunction().getAnArgument()
+  }
 }
 
 module PotentiallyExposedSystemData = TaintTracking::Global<PotentiallyExposedSystemDataConfig>;