[PATCH] D41384: [analyzer] Suppress false positive warnings form security.insecureAPI.strcpy

[András Leitereg via Phabricator via cfe-commits]

leanil updated this revision to Diff 135795.
leanil marked an inline comment as done.
leanil added a comment.

Use `getTypeSizeInChars` to get array size.


https://reviews.llvm.org/D41384

Files:
  lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp
  test/Analysis/security-syntax-checks.m


Index: test/Analysis/security-syntax-checks.m
===================================================================
--- test/Analysis/security-syntax-checks.m
+++ test/Analysis/security-syntax-checks.m
@@ -146,6 +146,16 @@
   strcpy(x, y); //expected-warning{{Call to function 'strcpy' is insecure as it does not provide bounding of the memory buffer. Replace unbounded copy functions with analogous functions that support length arguments such as 'strlcpy'. CWE-119}}
 }
 
+void test_strcpy_2() {
+  char x[4];
+  strcpy(x, "abcd"); //expected-warning{{Call to function 'strcpy' is insecure as it does not provide bounding of the memory buffer. Replace unbounded copy functions with analogous functions that support length arguments such as 'strlcpy'. CWE-119}}
+}
+
+void test_strcpy_safe() {
+  char x[5];
+  strcpy(x, "abcd");
+}
+
 //===----------------------------------------------------------------------===
 // strcat()
 //===----------------------------------------------------------------------===
Index: lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp
===================================================================
--- lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp
+++ lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp
@@ -510,6 +510,17 @@
   if (!checkCall_strCommon(CE, FD))
     return;
 
+  const auto *Target = CE->getArg(0)->IgnoreImpCasts(),
+             *Source = CE->getArg(1)->IgnoreImpCasts();
+  if (const auto *DeclRef = dyn_cast<DeclRefExpr>(Target))
+    if (const auto *Array = dyn_cast<ConstantArrayType>(DeclRef->getType())) {
+      auto ArraySize = BR.getContext().getTypeSizeInChars(Array).getQuantity();
+      if (const auto *String = dyn_cast<StringLiteral>(Source)) {
+        if (ArraySize >= String->getLength() + 1)
+          return;
+      }
+    }
+
   // Issue a warning.
   PathDiagnosticLocation CELoc =
     PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);


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