[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 321693.
ASDenysPetrov added a comment.

Updated. Rolled the fix over the evalCast refactoring.


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

https://reviews.llvm.org/D89055

Files:
  clang/lib/StaticAnalyzer/Core/SValBuilder.cpp
  clang/test/Analysis/casts.c
  clang/test/Analysis/string.c


Index: clang/test/Analysis/string.c
===================================================================
--- clang/test/Analysis/string.c
+++ clang/test/Analysis/string.c
@@ -363,6 +363,20 @@
     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
+}
+
+// PR49007
+char f(char ***c, int *i) {
+  *(void **)c = i + 1;
+  return (**c)[0]; // no-crash
+}
+
 //===----------------------------------------------------------------------===
 // stpcpy()
 //===----------------------------------------------------------------------===
Index: clang/test/Analysis/casts.c
===================================================================
--- clang/test/Analysis/casts.c
+++ clang/test/Analysis/casts.c
@@ -245,3 +245,8 @@
   return a * a;
 }
 
+void no_crash_reinterpret_char_as_uchar(char ***a, int *b) {
+  *(unsigned char **)a = (unsigned char *)b;
+  if (**a == 0) // no-crash
+    ;
+}
Index: clang/lib/StaticAnalyzer/Core/SValBuilder.cpp
===================================================================
--- clang/lib/StaticAnalyzer/Core/SValBuilder.cpp
+++ clang/lib/StaticAnalyzer/Core/SValBuilder.cpp
@@ -731,8 +731,8 @@
       // pointers as well.
       // FIXME: We really need a single good function to perform casts for us
       // correctly every time we need it.
+      const MemRegion *R = V.getRegion();
       if (CastTy->isPointerType() && !CastTy->isVoidPointerType()) {
-        const MemRegion *R = V.getRegion();
         if (const auto *SR = dyn_cast<SymbolicRegion>(R)) {
           QualType SRTy = SR->getSymbol()->getType();
           if (!hasSameUnqualifiedPointeeType(SRTy, CastTy)) {
@@ -741,6 +741,13 @@
           }
         }
       }
+      // Next fixes pointer dereference using type different from its initial
+      // one. See PR37503 and PR49007 for details.
+      if (const auto *ER = dyn_cast<ElementRegion>(R)) {
+        R = StateMgr.getStoreManager().castRegion(ER, CastTy);
+        return loc::MemRegionVal(R);
+      }
+
       return V;
     }
 


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