Make getSizeMult() functional.

Author: criemen

cpp/ql/src/semmle/code/cpp/models/implementations/Allocation.qll

@@ -261,7 +261,7 @@ private predicate deconstructSizeExpr(Expr sizeExpr, Expr lengthExpr, int sizeof
   exists(SizeofOperator sizeofOp |
     sizeofOp = sizeExpr.(MulExpr).getAnOperand() and
     lengthExpr = sizeExpr.(MulExpr).getAnOperand() and
-    sizeofOp != lengthExpr and
+    not lengthExpr instanceof SizeofOperator and
     sizeof = sizeofOp.getValue().toInt()
   )
   or

cpp/ql/test/library-tests/allocators/allocators.cpp

@@ -159,4 +159,5 @@ void testMalloc(size_t count) {
   malloc(count * sizeof(int));
   malloc(count * sizeof(int) + 1);
   malloc(((int) count) * sizeof(void *));
+  malloc(sizeof(void*) * sizeof(int));
 }

cpp/ql/test/library-tests/allocators/allocators.expected

@@ -91,6 +91,7 @@ allocationExprs
 | allocators.cpp:159:3:159:8 | call to malloc | getSizeExpr = count, getSizeMult = 4, requiresDealloc |
 | allocators.cpp:160:3:160:8 | call to malloc | getSizeExpr = ... + ..., getSizeMult = 1, requiresDealloc |
 | allocators.cpp:161:3:161:8 | call to malloc | getSizeExpr = count, getSizeMult = 8, requiresDealloc |
+| allocators.cpp:162:3:162:8 | call to malloc | getSizeExpr = ... * ..., requiresDealloc |
 deallocationFunctions
 | allocators.cpp:11:6:11:20 | operator delete | getFreedArg = 0 |
 | allocators.cpp:12:6:12:22 | operator delete[] | getFreedArg = 0 |