Detect source location overflow due includes

Summary:
As discussed in http://lists.llvm.org/pipermail/cfe-dev/2019-October/063459.html
the overflow of the souce locations (limited to 2^31 chars) can generate all sorts of
weird things (bogus warnings, hangs, crashes, miscompilation and correct compilation).
In debug mode this assert would fail. So it might be a good start, as in PR42301,
to detect the failure and exit with a proper error message.

Reviewers: rsmith, thakis, miyuki

Reviewed By: miyuki

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D70183

1 files changed, 6 insertions, 4 deletions

diff --git a/clang/lib/Basic/SourceManager.cpp b/clang/lib/Basic/SourceManager.cpp
index 73f2ae9..187c33a 100644
--- a/clang/lib/Basic/SourceManager.cpp
+++ b/clang/lib/Basic/SourceManager.cpp
@@ -577,13 +577,15 @@ FileID SourceManager::createFileID(const ContentCache *File, StringRef Filename,
     SLocEntryLoaded[Index] = true;
     return FileID::get(LoadedID);
   }
+  unsigned FileSize = File->getSize();
+  if (!(NextLocalOffset + FileSize + 1 > NextLocalOffset &&
+        NextLocalOffset + FileSize + 1 <= CurrentLoadedOffset)) {
+    Diag.Report(IncludePos, diag::err_include_too_large);
+    return FileID();
+  }
   LocalSLocEntryTable.push_back(
       SLocEntry::get(NextLocalOffset,
                      FileInfo::get(IncludePos, File, FileCharacter, Filename)));
-  unsigned FileSize = File->getSize();
-  assert(NextLocalOffset + FileSize + 1 > NextLocalOffset &&
-         NextLocalOffset + FileSize + 1 <= CurrentLoadedOffset &&
-         "Ran out of source locations!");
   // We do a +1 here because we want a SourceLocation that means "the end of the
   // file", e.g. for the "no newline at the end of the file" diagnostic.
   NextLocalOffset += FileSize + 1;