[Lldb-commits] [lldb] [lldb] Oversized DW_OP_piece triggers an unbounded allocation and aborts LLDB (PR #209397)

[Alexsander Borges Damaceno via lldb-commits]

https://github.com/AlexsanderDamaceno updated https://github.com/llvm/llvm-project/pull/209397

>From 4596168d38ca0c7c39a7fc97c68dd54d6cfb44ca Mon Sep 17 00:00:00 2001
From: AlexsanderDamaceno <aemgbo at gmail.com>
Date: Tue, 14 Jul 2026 05:16:18 -0300
Subject: [PATCH] E

---
 lldb/source/Expression/DWARFExpression.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/lldb/source/Expression/DWARFExpression.cpp b/lldb/source/Expression/DWARFExpression.cpp
index c4c86b408accd..12ae9d4ecdcd1 100644
--- a/lldb/source/Expression/DWARFExpression.cpp
+++ b/lldb/source/Expression/DWARFExpression.cpp
@@ -1107,6 +1107,15 @@ static llvm::Error Evaluate_DW_OP_piece(EvalContext &eval_ctx,
   if (piece_byte_size == 0)
     return llvm::Error::success();
 
+  // A single piece of a variable's location can never legitimately be
+  // this large. 
+  constexpr uint64_t kMaxDWARFPieceByteSize = 1024 * 1024 * 1024; // 1GB
+  if (piece_byte_size > kMaxDWARFPieceByteSize)
+    return llvm::createStringError(
+        "DW_OP_piece(%" PRIu64 ") is larger than the maximum allowed "
+        "size of %" PRIu64 " bytes",
+         piece_byte_size, kMaxDWARFPieceByteSize);
+
   Value curr_piece;
 
   if (eval_ctx.stack.empty()) {