[clang] bd7bce2 - Fix null-deref thanks to an attribute on a global declarator chunk (#83611)
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cfe-commits at lists.llvm.org
Mon Mar 4 09:25:34 PST 2024
Author: Erich Keane
Date: 2024-03-04T09:25:29-08:00
New Revision: bd7bce2c8465e9cb36a823846a52c9f553502575
URL: https://github.com/llvm/llvm-project/commit/bd7bce2c8465e9cb36a823846a52c9f553502575
DIFF: https://github.com/llvm/llvm-project/commit/bd7bce2c8465e9cb36a823846a52c9f553502575.diff
LOG: Fix null-deref thanks to an attribute on a global declarator chunk (#83611)
This was reported (sort of) in a PR: #77703. The problem is that a
declarator 'owns' an attributes allocation via an `AttributePool`.
However, this example tries to copy a DeclaratorChunk from one
Declarator to another, so when the temporary Declarator goes out of
scope, it deletes the attribute it has tried to pass on via the chunk.
This patch ensures that we copy the 'ownership' of the attribute
correctly, and adds an assert to catch any other casess where this
happens.
Additionally, this was put in as a bug report, so this
Fixes #83611
Added:
clang/test/Parser/cxx-declarator-attribute-crash.cpp
Modified:
clang/docs/ReleaseNotes.rst
clang/include/clang/Sema/DeclSpec.h
clang/include/clang/Sema/ParsedAttr.h
clang/lib/Parse/ParseDecl.cpp
clang/lib/Sema/ParsedAttr.cpp
Removed:
################################################################################
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index c381da7e354c70..806dc62cc55d9e 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -295,7 +295,9 @@ Bug Fixes to C++ Support
of templates. Previously we were diagnosing on any non-function template
instead of only on class, alias, and variable templates, as last updated by
CWG2032. Fixes (#GH83461)
-
+- Fixed an issue where an attribute on a declarator would cause the attribute to
+ be destructed prematurely. This fixes a pair of Chromium that were brought to
+ our attention by an attempt to fix in (#GH77703). Fixes (#GH83611).
Bug Fixes to AST Handling
^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/include/clang/Sema/DeclSpec.h b/clang/include/clang/Sema/DeclSpec.h
index 316e8071169a3a..a176159707486c 100644
--- a/clang/include/clang/Sema/DeclSpec.h
+++ b/clang/include/clang/Sema/DeclSpec.h
@@ -2359,11 +2359,27 @@ class Declarator {
SetRangeEnd(EndLoc);
}
+ /// AddTypeInfo - Add a chunk to this declarator. Also extend the range to
+ /// EndLoc, which should be the last token of the chunk. This overload is for
+ /// copying a 'chunk' from another declarator, so it takes the pool that the
+ /// other Declarator owns so that it can 'take' the attributes from it.
+ void AddTypeInfo(const DeclaratorChunk &TI, AttributePool &OtherPool,
+ SourceLocation EndLoc) {
+ DeclTypeInfo.push_back(TI);
+ getAttributePool().takeFrom(DeclTypeInfo.back().getAttrs(), OtherPool);
+
+ if (!EndLoc.isInvalid())
+ SetRangeEnd(EndLoc);
+ }
+
/// AddTypeInfo - Add a chunk to this declarator. Also extend the range to
/// EndLoc, which should be the last token of the chunk.
void AddTypeInfo(const DeclaratorChunk &TI, SourceLocation EndLoc) {
DeclTypeInfo.push_back(TI);
+ assert(TI.AttrList.empty() &&
+ "Cannot add a declarator chunk with attributes with this overload");
+
if (!EndLoc.isInvalid())
SetRangeEnd(EndLoc);
}
diff --git a/clang/include/clang/Sema/ParsedAttr.h b/clang/include/clang/Sema/ParsedAttr.h
index 8c3ba39031aad8..e3857b2f07d9e0 100644
--- a/clang/include/clang/Sema/ParsedAttr.h
+++ b/clang/include/clang/Sema/ParsedAttr.h
@@ -680,6 +680,7 @@ class AttributeFactory {
~AttributeFactory();
};
+class ParsedAttributesView;
class AttributePool {
friend class AttributeFactory;
friend class ParsedAttributes;
@@ -734,6 +735,10 @@ class AttributePool {
pool.Attrs.clear();
}
+ /// Removes the attributes from \c List, which are owned by \c Pool, and adds
+ /// them at the end of this \c AttributePool.
+ void takeFrom(ParsedAttributesView &List, AttributePool &Pool);
+
ParsedAttr *create(IdentifierInfo *attrName, SourceRange attrRange,
IdentifierInfo *scopeName, SourceLocation scopeLoc,
ArgsUnion *args, unsigned numArgs, ParsedAttr::Form form,
@@ -816,6 +821,7 @@ class AttributePool {
};
class ParsedAttributesView {
+ friend class AttributePool;
using VecTy = llvm::SmallVector<ParsedAttr *>;
using SizeType = decltype(std::declval<VecTy>().size());
diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index edfab11c37cf0f..ccbfea6a66fba7 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -7928,7 +7928,7 @@ void Parser::ParseMisplacedBracketDeclarator(Declarator &D) {
// Adding back the bracket info to the end of the Declarator.
for (unsigned i = 0, e = TempDeclarator.getNumTypeObjects(); i < e; ++i) {
const DeclaratorChunk &Chunk = TempDeclarator.getTypeObject(i);
- D.AddTypeInfo(Chunk, SourceLocation());
+ D.AddTypeInfo(Chunk, TempDeclarator.getAttributePool(), SourceLocation());
}
// The missing identifier would have been diagnosed in ParseDirectDeclarator.
diff --git a/clang/lib/Sema/ParsedAttr.cpp b/clang/lib/Sema/ParsedAttr.cpp
index 06c213267c7ef5..6abc90336c9946 100644
--- a/clang/lib/Sema/ParsedAttr.cpp
+++ b/clang/lib/Sema/ParsedAttr.cpp
@@ -100,6 +100,12 @@ void AttributePool::takePool(AttributePool &pool) {
pool.Attrs.clear();
}
+void AttributePool::takeFrom(ParsedAttributesView &List, AttributePool &Pool) {
+ assert(&Pool != this && "AttributePool can't take attributes from itself");
+ llvm::for_each(List.AttrList, [&Pool](ParsedAttr *A) { Pool.remove(A); });
+ Attrs.insert(Attrs.end(), List.AttrList.begin(), List.AttrList.end());
+}
+
namespace {
#include "clang/Sema/AttrParsedAttrImpl.inc"
diff --git a/clang/test/Parser/cxx-declarator-attribute-crash.cpp b/clang/test/Parser/cxx-declarator-attribute-crash.cpp
new file mode 100644
index 00000000000000..3b989a659db569
--- /dev/null
+++ b/clang/test/Parser/cxx-declarator-attribute-crash.cpp
@@ -0,0 +1,8 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+// expected-error at +5{{brackets are not allowed here}}
+// expected-error at +4{{a type specifier is required for all declarations}}
+// expected-warning at +3{{unknown attribute 'h' ignored}}
+// expected-error at +2{{definition of variable with array type}}
+// expected-error at +1{{expected ';'}}
+[][[h]]l
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