[PATCH] D129269: [analyzer] Fix use of length in CStringChecker

[Vince Bridgers via Phabricator via cfe-commits]

vabridgers updated this revision to Diff 443101.
vabridgers added a comment.

a proposal to handle embedded null case caught by @steakhal


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D129269/new/

https://reviews.llvm.org/D129269

Files:
  clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp
  clang/test/Analysis/string.c


Index: clang/test/Analysis/string.c
===================================================================
--- clang/test/Analysis/string.c
+++ clang/test/Analysis/string.c
@@ -1652,3 +1652,8 @@
   __builtin___memset_chk(&x, 0, sizeof(x), __builtin_object_size(&x, 0));
   clang_analyzer_eval(x == 0); // expected-warning{{TRUE}}
 }
+
+void strcpy_no_overflow_2(char *y) {
+  char x[3];
+  strcpy(x, "12\0");
+}
Index: clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp
===================================================================
--- clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp
+++ clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp
@@ -848,7 +848,15 @@
     SValBuilder &svalBuilder = C.getSValBuilder();
     QualType sizeTy = svalBuilder.getContext().getSizeType();
     const StringLiteral *strLit = cast<StringRegion>(MR)->getStringLiteral();
-    return svalBuilder.makeIntVal(strLit->getByteLength(), sizeTy);
+    unsigned countx = 0;
+    // get the number of string literal characters by the target's "code unit"
+    // size, checking for an embedded literal of 0 up to the string literal's
+    // length.
+    for (countx = 0;
+         countx < strLit->getLength() && (strLit->getCodeUnit(countx) != 0);
+         countx++)
+      ;
+    return svalBuilder.makeIntVal(countx, sizeTy);
   }
   case MemRegion::SymbolicRegionKind:
   case MemRegion::AllocaRegionKind:


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