[clang] c671041 - Check for resource exhaustion when recursively parsing declarators

[Aaron Ballman via cfe-commits]

Author: Aaron Ballman
Date: 2022-05-12T13:20:35-04:00
New Revision: c671041720347c9deb35b1165ee6b6bb88abf07a

URL: https://github.com/llvm/llvm-project/commit/c671041720347c9deb35b1165ee6b6bb88abf07a
DIFF: https://github.com/llvm/llvm-project/commit/c671041720347c9deb35b1165ee6b6bb88abf07a.diff

LOG: Check for resource exhaustion when recursively parsing declarators

With sufficiently tortured code, it's possible to cause a stack
overflow when parsing declarators. Thus, we now check for resource
exhaustion when recursively parsing declarators so that we can at least
warn the user we're about to crash before we actually crash.

Fixes #51642

Differential Revision: https://reviews.llvm.org/D124915

Added: 
    

Modified: 
    clang/docs/ReleaseNotes.rst
    clang/lib/Parse/ParseDecl.cpp

Removed: 
    


################################################################################
diff  --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index e7dd0d1d6e910..7c25456adb25a 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -222,7 +222,9 @@ Improvements to Clang's diagnostics
   on such language mode, ``-Wpre-c2x-compat`` and ``-Wpre-c++2b-compat``
   diagnostic flags report a compatibility issue.
   Fixes `Issue 55306 <https://github.com/llvm/llvm-project/issues/55306>`_.
-
+- Clang now checks for stack resource exhaustion when recursively parsing
+  declarators in order to give a diagnostic before we run out of stack space.
+  This fixes `Issue 51642 <https://github.com/llvm/llvm-project/issues/51642>`_.
 
 Non-comprehensive list of changes in this release
 -------------------------------------------------

diff  --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index 89e13cf5c90f9..306644fc4b21d 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -5765,11 +5765,12 @@ void Parser::ParseTypeQualifierListOpt(
 }
 
 /// ParseDeclarator - Parse and verify a newly-initialized declarator.
-///
 void Parser::ParseDeclarator(Declarator &D) {
   /// This implements the 'declarator' production in the C grammar, then checks
   /// for well-formedness and issues diagnostics.
-  ParseDeclaratorInternal(D, &Parser::ParseDirectDeclarator);
+  Actions.runWithSufficientStackSpace(D.getBeginLoc(), [&] {
+    ParseDeclaratorInternal(D, &Parser::ParseDirectDeclarator);
+  });
 }
 
 static bool isPtrOperatorToken(tok::TokenKind Kind, const LangOptions &Lang,
@@ -5880,7 +5881,9 @@ void Parser::ParseDeclaratorInternal(Declarator &D,
       D.ExtendWithDeclSpec(DS);
 
       // Recurse to parse whatever is left.
-      ParseDeclaratorInternal(D, DirectDeclParser);
+      Actions.runWithSufficientStackSpace(D.getBeginLoc(), [&] {
+        ParseDeclaratorInternal(D, DirectDeclParser);
+      });
 
       // Sema will have to catch (syntactically invalid) pointers into global
       // scope. It has to catch pointers into namespace scope anyway.
@@ -5929,7 +5932,8 @@ void Parser::ParseDeclaratorInternal(Declarator &D,
     D.ExtendWithDeclSpec(DS);
 
     // Recursively parse the declarator.
-    ParseDeclaratorInternal(D, DirectDeclParser);
+    Actions.runWithSufficientStackSpace(
+        D.getBeginLoc(), [&] { ParseDeclaratorInternal(D, DirectDeclParser); });
     if (Kind == tok::star)
       // Remember that we parsed a pointer type, and remember the type-quals.
       D.AddTypeInfo(DeclaratorChunk::getPointer(
@@ -5974,7 +5978,8 @@ void Parser::ParseDeclaratorInternal(Declarator &D,
     }
 
     // Recursively parse the declarator.
-    ParseDeclaratorInternal(D, DirectDeclParser);
+    Actions.runWithSufficientStackSpace(
+        D.getBeginLoc(), [&] { ParseDeclaratorInternal(D, DirectDeclParser); });
 
     if (D.getNumTypeObjects() > 0) {
       // C++ [dcl.ref]p4: There shall be no references to references.