[PATCH] D89055: [analyzer] Wrong type cast occures during pointer dereferencing after type punning

[Denys Petrov via Phabricator via cfe-commits]

ASDenysPetrov updated this revision to Diff 297579.
ASDenysPetrov added a comment.

Updat patch due to suggestions and fixed formating.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D89055/new/

https://reviews.llvm.org/D89055

Files:
  clang/lib/StaticAnalyzer/Core/Store.cpp
  clang/test/Analysis/nonloc-as-loc-crash.c
  clang/test/Analysis/string.c


Index: clang/test/Analysis/string.c
===================================================================
--- clang/test/Analysis/string.c
+++ clang/test/Analysis/string.c
@@ -363,6 +363,14 @@
     strcpy(x, y); // no-warning
 }
 
+// PR37503
+void *get_void_ptr();
+char ***type_punned_ptr;
+void strcpy_no_assertion(char c) {
+  *(unsigned char **)type_punned_ptr = (unsigned char *)(get_void_ptr());
+  strcpy(**type_punned_ptr, &c); // no-crash
+}
+
 //===----------------------------------------------------------------------===
 // stpcpy()
 //===----------------------------------------------------------------------===
Index: clang/test/Analysis/nonloc-as-loc-crash.c
===================================================================
--- /dev/null
+++ clang/test/Analysis/nonloc-as-loc-crash.c
@@ -0,0 +1,12 @@
+// RUN: %clang_analyze_cc1 -analyzer-checker=core -verify %s
+// expected-no-diagnostics
+
+void test(int *a, char ***b, float *c) {
+  *(unsigned char **)b = (unsigned char *)a;
+  if (**b == 0) // no-crash
+    ;
+
+  *(unsigned char **)b = (unsigned char *)c;
+  if (**b == 0) // no-crash
+    ;
+}
Index: clang/lib/StaticAnalyzer/Core/Store.cpp
===================================================================
--- clang/lib/StaticAnalyzer/Core/Store.cpp
+++ clang/lib/StaticAnalyzer/Core/Store.cpp
@@ -426,12 +426,17 @@
   // We might need to do that for non-void pointers as well.
   // FIXME: We really need a single good function to perform casts for us
   // correctly every time we need it.
-  if (castTy->isPointerType() && !castTy->isVoidPointerType())
+  if (castTy->isPointerType() && !castTy->isVoidPointerType()) {
     if (const auto *SR = dyn_cast_or_null<SymbolicRegion>(V.getAsRegion())) {
       QualType sr = SR->getSymbol()->getType();
       if (!hasSameUnqualifiedPointeeType(sr, castTy))
-          return loc::MemRegionVal(castRegion(SR, castTy));
+        return loc::MemRegionVal(castRegion(SR, castTy));
     }
+    // Next fixes pointer dereference using type different from its initial one
+    // See PR37503 for details
+    if (const auto *SR = dyn_cast_or_null<ElementRegion>(V.getAsRegion()))
+      return loc::MemRegionVal(castRegion(SR, castTy));
+  }
 
   return svalBuilder.dispatchCast(V, castTy);
 }


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