[clang] [Clang][Sema] Add fortify warnings for fread, fwrite, and fgets (PR #204337)

[Nick Desaulniers via cfe-commits]

Radovan =?utf-8?q?Božić?= <radovan.bozic at htecgroup.com>,
Radovan =?utf-8?q?Božić?= <radovan.bozic at htecgroup.com>
Message-ID:
In-Reply-To: <llvm.org/llvm/llvm-project/pull/204337 at github.com>


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@@ -1496,7 +1522,24 @@ void Sema::checkFortifiedBuiltinMemoryFunction(FunctionDecl *FD,
     Checker.checkSourceOverread(/*SrcArgIdx=*/0, /*SizeArgIdx=*/2);
     break;
   }
-
+  case Builtin::BIfread: {
+    DiagID = diag::warn_fortify_source_overflow;
+    SourceSize = Checker.ComputeExplicitObjectSizeArgumentProduct(1, 2);
+    DestinationSize = Checker.ComputeSizeArgument(0);
+    break;
+  }
+  case Builtin::BIfwrite: {
+    DiagID = diag::warn_fortify_source_overread;
+    SourceSize = Checker.ComputeExplicitObjectSizeArgumentProduct(1, 2);
+    DestinationSize = Checker.ComputeSizeArgument(0);
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nickdesaulniers wrote:

For `fwrite`, arg zero is the _source_ buffer, not the destination, so assigning to `DestinationSize` works, but it confusing, IMO.

Rather than `SourceSize`/`DestinationSize`; I think `BufferSize` / `AccessSize` (or `RequestedSize`) might be clearer between reads AND writes.

https://github.com/llvm/llvm-project/pull/204337