[lldb/DWARF] Make sure bad abbreviation codes do not crash lldb

lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp

@@ -11,6 +11,7 @@
 #include <cassert>
 
 #include <algorithm>
+#include <limits>
 #include <optional>
 
 #include "llvm/Support/LEB128.h"
@@ -41,13 +42,23 @@ extern int g_verbose;
 // Extract a debug info entry for a given DWARFUnit from the data
 // starting at the offset in offset_ptr
 bool DWARFDebugInfoEntry::Extract(const DWARFDataExtractor &data,
-                                  const DWARFUnit *cu,
+                                  const DWARFUnit &unit,
                                   lldb::offset_t *offset_ptr) {
   m_offset = *offset_ptr;
+  auto report_error = [&](const char *fmt, const auto &...vals) {
+    unit.GetSymbolFileDWARF().GetObjectFile()->GetModule()->ReportError(
+        "[{0:x16}]: {1}, please file a bug and "
+        "attach the file at the start of this error message",
+        static_cast<uint64_t>(m_offset), llvm::formatv(fmt, vals...));
+    *offset_ptr = std::numeric_limits<lldb::offset_t>::max();
+    return false;
+  };
+
   m_parent_idx = 0;
   m_sibling_idx = 0;
   const uint64_t abbr_idx = data.GetULEB128(offset_ptr);
-  lldbassert(abbr_idx <= UINT16_MAX);
+  if (abbr_idx > std::numeric_limits<uint16_t>::max())
+    return report_error("abbreviation code {0} too big", abbr_idx);
   m_abbr_idx = abbr_idx;
 
   if (m_abbr_idx == 0) {
@@ -56,31 +67,18 @@ bool DWARFDebugInfoEntry::Extract(const DWARFDataExtractor &data,
     return true; // NULL debug tag entry
   }
 
-  const auto *abbrevDecl = GetAbbreviationDeclarationPtr(cu);
-  if (abbrevDecl == nullptr) {
-    cu->GetSymbolFileDWARF().GetObjectFile()->GetModule()->ReportError(
-        "[{0:x16}]: invalid abbreviation code {1}, "
-        "please file a bug and "
-        "attach the file at the start of this error message",
-        (uint64_t)m_offset, (unsigned)abbr_idx);
-    // WE can't parse anymore if the DWARF is borked...
-    *offset_ptr = UINT32_MAX;
-    return false;
-  }
+  const auto *abbrevDecl = GetAbbreviationDeclarationPtr(&unit);
+  if (abbrevDecl == nullptr)
+    return report_error("invalid abbreviation code {0}", abbr_idx);
+
   m_tag = abbrevDecl->getTag();
   m_has_children = abbrevDecl->hasChildren();
   // Skip all data in the .debug_info or .debug_types for the attributes
   for (const auto &attribute : abbrevDecl->attributes()) {
-    if (DWARFFormValue::SkipValue(attribute.Form, data, offset_ptr, cu))
+    if (DWARFFormValue::SkipValue(attribute.Form, data, offset_ptr, &unit))
       continue;
 
-    cu->GetSymbolFileDWARF().GetObjectFile()->GetModule()->ReportError(
-        "[{0:x16}]: Unsupported DW_FORM_{1:x}, please file a bug "
-        "and "
-        "attach the file at the start of this error message",
-        (uint64_t)m_offset, (unsigned)attribute.Form);
-    *offset_ptr = m_offset;
-    return false;
+    return report_error("Unsupported DW_FORM_{1:x}", attribute.Form);
   }
   return true;
 }

lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.h

@@ -49,7 +49,7 @@ class DWARFDebugInfoEntry {
   void BuildFunctionAddressRangeTable(DWARFUnit *cu,
                                       DWARFDebugAranges *debug_aranges) const;
 
-  bool Extract(const DWARFDataExtractor &data, const DWARFUnit *cu,
+  bool Extract(const DWARFDataExtractor &data, const DWARFUnit &cu,
                lldb::offset_t *offset_ptr);
 
   using Recurse = DWARFBaseDIE::Recurse;

lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp

@@ -63,7 +63,7 @@ void DWARFUnit::ExtractUnitDIENoDwoIfNeeded() {
   // parse
   const DWARFDataExtractor &data = GetData();
   if (offset < GetNextUnitOffset() &&
-      m_first_die.Extract(data, this, &offset)) {
+      m_first_die.Extract(data, *this, &offset)) {
     AddUnitDIE(m_first_die);
     return;
   }
@@ -242,7 +242,7 @@ void DWARFUnit::ExtractDIEsRWLocked() {
   die_index_stack.reserve(32);
   die_index_stack.push_back(0);
   bool prev_die_had_children = false;
-  while (offset < next_cu_offset && die.Extract(data, this, &offset)) {
+  while (offset < next_cu_offset && die.Extract(data, *this, &offset)) {
     const bool null_die = die.IsNULL();
     if (depth == 0) {
       assert(m_die_array.empty() && "Compile unit DIE already added");
@@ -670,7 +670,7 @@ DWARFUnit::GetDIE(dw_offset_t die_offset) {
 
 llvm::StringRef DWARFUnit::PeekDIEName(dw_offset_t die_offset) {
   DWARFDebugInfoEntry die;
-  if (!die.Extract(GetData(), this, &die_offset))
+  if (!die.Extract(GetData(), *this, &die_offset))
     return llvm::StringRef();
 
   // Does die contain a DW_AT_Name?

lldb/test/Shell/SymbolFile/DWARF/x86/invalid_abbreviation.s

@@ -0,0 +1,47 @@
+# REQUIRES: x86
+
+# RUN: llvm-mc -triple=x86_64-pc-linux -filetype=obj %s > %t
+# RUN: %lldb %t \
+# RUN:   -o exit 2>&1 | FileCheck %s
+
+# CHECK-DAG: error: {{.*}} [0x0000000000000022]: abbreviation code 65536 too big, please file a bug and attach the file at the start of this error message
+# CHECK-DAG: error: {{.*}} [0x0000000000000048]: invalid abbreviation code 47, please file a bug and attach the file at the start of this error message
+
+
+        .section        .debug_abbrev,"",@progbits
+        .uleb128 65535                  # Largest representable Abbreviation Code
+        .byte   17                      # DW_TAG_compile_unit
+        .byte   1                       # DW_CHILDREN_yes
+        .byte   37                      # DW_AT_producer
+        .byte   8                       # DW_FORM_string
+        .byte   0                       # EOM(1)
+        .byte   0                       # EOM(2)
+        .byte   0                       # EOM(3)
+
+        .section        .debug_info,"",@progbits
+.Lcu_begin0:
+        .long   .Ldebug_info_end0-.Ldebug_info_start0 # Length of Unit
+.Ldebug_info_start0:
+        .short  5                       # DWARF version number
+        .byte   1                       # DWARF Unit Type
+        .byte   8                       # Address Size (in bytes)
+        .long   .debug_abbrev           # Offset Into Abbrev. Section
+        .uleb128 65535                  # DW_TAG_compile_unit
+        .asciz  "Hand-written DWARF"    # DW_AT_producer
+        .uleb128 65536                  # Unrepresentable abbreviation
+        .byte   0                       # End Of Children Mark
+.Ldebug_info_end0:
+
+        .section        .debug_info,"",@progbits
+.Lcu_begin1:
+        .long   .Ldebug_info_end1-.Ldebug_info_start1 # Length of Unit
+.Ldebug_info_start1:
+        .short  5                       # DWARF version number
+        .byte   1                       # DWARF Unit Type
+        .byte   8                       # Address Size (in bytes)
+        .long   .debug_abbrev           # Offset Into Abbrev. Section
+        .uleb128 65535                  # DW_TAG_compile_unit
+        .asciz  "Hand-written DWARF"    # DW_AT_producer
+        .byte   47                      # Missing abbreviation
+        .byte   0                       # End Of Children Mark
+.Ldebug_info_end1: