| Issue |
181735
|
| Summary |
Clang Frontend Crash - Compiling Malformed Input Containing Recursive Include and Unbalanced Parentheses
|
| Labels |
clang
|
| Assignees |
|
| Reporter |
apbenson00
|
Clang crashes when compiling the following malformed C input. This issue was discovered via fuzzing with AFL++ and minimized by hand. The crash is reproducible.
Tested on Clang 21.1.8 on Ubuntu 25 and Clang 21.1.0 on CompilerExplorer.
### Code:
```
func() {
#include __FILE__
(((((((
```
### Command:
```
clang ./crashing_file.c
```
### Expected Output:
Syntax Error and safe termination
### Actual Behavior
Clang crashes with segmentation fault during parsing.
### Portion of the Stack Trace:
```
"Stacktrace": [
"#0 0x000055555ea2e3c4 in clang::Lexer::LexTokenInternal (this=0x55556218b810, Result=..., TokAtPhysicalStartOfLine=<error reading variable: Cannot access memory at address 0x7fffff7fed37>) at clang/lib/Lex/Lexer.cpp:3740",
"#1 0x000055555eb199ba in clang::Preprocessor::Lex (this=0x1, Result=...) at clang/lib/Lex/Preprocessor.cpp:896",
"#2 0x000055555c3d82aa in clang::Parser::ConsumeParen (this=<optimized out>) at clang/include/clang/Parse/Parser.h:642",
"#3 clang::BalancedDelimiterTracker::consumeOpen (this=0x7fffff7ff128) at clang/include/clang/Parse/RAIIObjectsForParser.h:471",
"#4 clang::Parser::ParseParenExpression (this=this@entry=0x555562159280, ExprType=@0x7fffff7ffec0: clang::ParenParseOption::CastExpr, StopIfCastExpr=false, ParenBehavior=ParenBehavior@entry=clang::ParenExprKind::Unknown, CorrectionBehavior=clang::TypoCorrectionTypeBehavior::AllowBoth, CastTy=..., RParenLoc=...) at clang/lib/Parse/ParseExpr.cpp:2618",
"#5 0x000055555c3d58ed in clang::Parser::ParseCastExpression (this=0x555562159280, ParseKind=ParseKind@entry=clang::CastParseKind::AnyCastExpr, isAddressOfOperand=<optimized out>, NotCastExpr=@0x7fffff800d37: false, CorrectionBehavior=(clang::TypoCorrectionTypeBehavior::AllowTypes | unknown: 0xfc), isVectorLiteral=false, NotPrimaryExpression=<optimized out>) at clang/lib/Parse/ParseExpr.cpp:763",
"#6 0x000055555c3cad9d in clang::Parser::ParseCastExpression (this=0x1, ParseKind=clang::CastParseKind::AnyCastExpr, isAddressOfOperand=false, CorrectionBehavior=(clang::TypoCorrectionTypeBehavior::AllowTypes | unknown: 0xfc), isVectorLiteral=false, NotPrimaryExpression=0x0) at clang/lib/Parse/ParseExpr.cpp:567",
"#7 clang::Parser::ParseAssignmentExpression (this=0x1, this@entry=0x555562159280, CorrectionBehavior=(clang::TypoCorrectionTypeBehavior::AllowTypes | unknown: 0xfc), CorrectionBehavior@entry=clang::TypoCorrectionTypeBehavior::AllowBoth) at clang/lib/Parse/ParseExpr.cpp:90",
```
### Environment:
clang version 21.1.8
OS: Ubuntu 25.04
Architecture: x86_64
RAM: 8GB
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