[DebugInfo] Add use of truncating data extractor to debug line parsing

This will ensure that nothing can ever start parsing data from a future
sequence and part-read data will be returned as 0 instead.

Reviewed by: aprantl, labath

Differential Revision: https://reviews.llvm.org/D80796

llvm/lib/DebugInfo/DWARF/DWARFDebugLine.cpp

@@ -721,14 +721,17 @@ Error DWARFDebugLine::LineTable::parse(
     ProgramLength = BytesRemaining;
   }
 
+  // Create a DataExtractor which can only see the data up to the end of the
+  // table, to prevent reading past the end.
   const uint64_t EndOffset = DebugLineOffset + ProgramLength;
+  DWARFDataExtractor TableData(DebugLineData, EndOffset);
 
   // See if we should tell the data extractor the address size.
-  if (DebugLineData.getAddressSize() == 0)
-    DebugLineData.setAddressSize(Prologue.getAddressSize());
+  if (TableData.getAddressSize() == 0)
+    TableData.setAddressSize(Prologue.getAddressSize());
   else
     assert(Prologue.getAddressSize() == 0 ||
-           Prologue.getAddressSize() == DebugLineData.getAddressSize());
+           Prologue.getAddressSize() == TableData.getAddressSize());
 
   ParsingState State(this, DebugLineOffset, RecoverableErrorHandler);
 
@@ -738,7 +741,7 @@ Error DWARFDebugLine::LineTable::parse(
       *OS << format("0x%08.08" PRIx64 ": ", *OffsetPtr);
 
     uint64_t OpcodeOffset = *OffsetPtr;
-    uint8_t Opcode = DebugLineData.getU8(OffsetPtr);
+    uint8_t Opcode = TableData.getU8(OffsetPtr);
 
     if (OS)
       *OS << format("%02.02" PRIx8 " ", Opcode);
@@ -746,7 +749,7 @@ Error DWARFDebugLine::LineTable::parse(
     if (Opcode == 0) {
       // Extended Opcodes always start with a zero opcode followed by
       // a uleb128 length so you can skip ones you don't know about
-      uint64_t Len = DebugLineData.getULEB128(OffsetPtr);
+      uint64_t Len = TableData.getULEB128(OffsetPtr);
       uint64_t ExtOffset = *OffsetPtr;
 
       // Tolerate zero-length; assume length is correct and soldier on.
@@ -756,7 +759,7 @@ Error DWARFDebugLine::LineTable::parse(
         continue;
       }
 
-      uint8_t SubOpcode = DebugLineData.getU8(OffsetPtr);
+      uint8_t SubOpcode = TableData.getU8(OffsetPtr);
       if (OS)
         *OS << LNExtendedString(SubOpcode);
       switch (SubOpcode) {
@@ -789,7 +792,7 @@ Error DWARFDebugLine::LineTable::parse(
         // Make sure the extractor knows the address size.  If not, infer it
         // from the size of the operand.
         {
-          uint8_t ExtractorAddressSize = DebugLineData.getAddressSize();
+          uint8_t ExtractorAddressSize = TableData.getAddressSize();
           uint64_t OpcodeAddressSize = Len - 1;
           if (ExtractorAddressSize != OpcodeAddressSize &&
               ExtractorAddressSize != 0)
@@ -812,13 +815,13 @@ Error DWARFDebugLine::LineTable::parse(
                 OpcodeAddressSize, ExtOffset));
             *OffsetPtr += OpcodeAddressSize;
           } else {
-            DebugLineData.setAddressSize(OpcodeAddressSize);
-            State.Row.Address.Address = DebugLineData.getRelocatedAddress(
+            TableData.setAddressSize(OpcodeAddressSize);
+            State.Row.Address.Address = TableData.getRelocatedAddress(
                 OffsetPtr, &State.Row.Address.SectionIndex);
 
             // Restore the address size if the extractor already had it.
             if (ExtractorAddressSize != 0)
-              DebugLineData.setAddressSize(ExtractorAddressSize);
+              TableData.setAddressSize(ExtractorAddressSize);
           }
 
           if (OS)
@@ -849,12 +852,12 @@ Error DWARFDebugLine::LineTable::parse(
         // the file register of the state machine.
         {
           FileNameEntry FileEntry;
-          const char *Name = DebugLineData.getCStr(OffsetPtr);
+          const char *Name = TableData.getCStr(OffsetPtr);
           FileEntry.Name =
               DWARFFormValue::createFromPValue(dwarf::DW_FORM_string, Name);
-          FileEntry.DirIdx = DebugLineData.getULEB128(OffsetPtr);
-          FileEntry.ModTime = DebugLineData.getULEB128(OffsetPtr);
-          FileEntry.Length = DebugLineData.getULEB128(OffsetPtr);
+          FileEntry.DirIdx = TableData.getULEB128(OffsetPtr);
+          FileEntry.ModTime = TableData.getULEB128(OffsetPtr);
+          FileEntry.Length = TableData.getULEB128(OffsetPtr);
           Prologue.FileNames.push_back(FileEntry);
           if (OS)
             *OS << " (" << Name << ", dir=" << FileEntry.DirIdx << ", mod_time="
@@ -864,7 +867,7 @@ Error DWARFDebugLine::LineTable::parse(
         break;
 
       case DW_LNE_set_discriminator:
-        State.Row.Discriminator = DebugLineData.getULEB128(OffsetPtr);
+        State.Row.Discriminator = TableData.getULEB128(OffsetPtr);
         if (OS)
           *OS << " (" << State.Row.Discriminator << ")";
         break;
@@ -913,7 +916,7 @@ Error DWARFDebugLine::LineTable::parse(
         // result to the address register of the state machine.
         {
           uint64_t AddrOffset = State.advanceAddr(
-              DebugLineData.getULEB128(OffsetPtr), Opcode, OpcodeOffset);
+              TableData.getULEB128(OffsetPtr), Opcode, OpcodeOffset);
           if (OS)
             *OS << " (" << AddrOffset << ")";
         }
@@ -922,7 +925,7 @@ Error DWARFDebugLine::LineTable::parse(
       case DW_LNS_advance_line:
         // Takes a single signed LEB128 operand and adds that value to
         // the line register of the state machine.
-        State.Row.Line += DebugLineData.getSLEB128(OffsetPtr);
+        State.Row.Line += TableData.getSLEB128(OffsetPtr);
         if (OS)
           *OS << " (" << State.Row.Line << ")";
         break;
@@ -930,7 +933,7 @@ Error DWARFDebugLine::LineTable::parse(
       case DW_LNS_set_file:
         // Takes a single unsigned LEB128 operand and stores it in the file
         // register of the state machine.
-        State.Row.File = DebugLineData.getULEB128(OffsetPtr);
+        State.Row.File = TableData.getULEB128(OffsetPtr);
         if (OS)
           *OS << " (" << State.Row.File << ")";
         break;
@@ -938,7 +941,7 @@ Error DWARFDebugLine::LineTable::parse(
       case DW_LNS_set_column:
         // Takes a single unsigned LEB128 operand and stores it in the
         // column register of the state machine.
-        State.Row.Column = DebugLineData.getULEB128(OffsetPtr);
+        State.Row.Column = TableData.getULEB128(OffsetPtr);
         if (OS)
           *OS << " (" << State.Row.Column << ")";
         break;
@@ -986,7 +989,7 @@ Error DWARFDebugLine::LineTable::parse(
         // requires the use of DW_LNS_advance_pc. Such assemblers, however,
         // can use DW_LNS_fixed_advance_pc instead, sacrificing compression.
         {
-          uint16_t PCOffset = DebugLineData.getRelocatedValue(2, OffsetPtr);
+          uint16_t PCOffset = TableData.getRelocatedValue(2, OffsetPtr);
           State.Row.Address.Address += PCOffset;
           if (OS)
             *OS
@@ -1009,7 +1012,7 @@ Error DWARFDebugLine::LineTable::parse(
       case DW_LNS_set_isa:
         // Takes a single unsigned LEB128 operand and stores it in the
         // column register of the state machine.
-        State.Row.Isa = DebugLineData.getULEB128(OffsetPtr);
+        State.Row.Isa = TableData.getULEB128(OffsetPtr);
         if (OS)
           *OS << " (" << (uint64_t)State.Row.Isa << ")";
         break;
@@ -1022,7 +1025,7 @@ Error DWARFDebugLine::LineTable::parse(
           assert(Opcode - 1U < Prologue.StandardOpcodeLengths.size());
           uint8_t OpcodeLength = Prologue.StandardOpcodeLengths[Opcode - 1];
           for (uint8_t I = 0; I < OpcodeLength; ++I) {
-            uint64_t Value = DebugLineData.getULEB128(OffsetPtr);
+            uint64_t Value = TableData.getULEB128(OffsetPtr);
             if (OS)
               *OS << format("Skipping ULEB128 value: 0x%16.16" PRIx64 ")\n",
                             Value);

llvm/test/tools/llvm-dwarfdump/X86/Inputs/debug_line_malformed.s

@@ -488,6 +488,36 @@
 .byte   0, 1, 1         # DW_LNE_end_sequence
 .Lunterminated_files_end:
 
+# Opcode extends past the end of the table, as claimed by the unit length field.
+.long   .Lextended_past_end_end - .Lextended_past_end_start # Length of Unit
+.Lextended_past_end_start:
+.short  4               # DWARF version number
+.long   .Lprologue_extended_past_end_end-.Lprologue_extended_past_end_start # Length of Prologue
+.Lprologue_extended_past_end_start:
+.byte   1               # Minimum Instruction Length
+.byte   1               # Maximum Operations per Instruction
+.byte   1               # Default is_stmt
+.byte   -5              # Line Base
+.byte   14              # Line Range
+.byte   13              # Opcode Base
+.byte   0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1 # Standard Opcode Lengths
+.asciz "dir1"           # Include table
+.asciz "dir2"
+.byte   0
+.asciz "file1"          # File table
+.byte   0, 0, 0
+.asciz "file2"
+.byte   1, 0, 0
+.byte   0
+.Lprologue_extended_past_end_end:
+.byte   0, 9, 2         # DW_LNE_set_address
+.quad   0xfeedfeed
+.byte   1               # DW_LNS_copy
+.byte   0, 9, 2         # DW_LNE_set_address
+.long   0xf001f000      # Truncated address (should be 8 bytes)
+.byte   0xf0, 0, 1
+.Lextended_past_end_end:
+
 # Trailing good section.
 .long   .Lunit_good_end - .Lunit_good_start # Length of Unit (DWARF-32 format)
 .Lunit_good_start:

llvm/test/tools/llvm-dwarfdump/X86/debug_line_invalid.test

@@ -33,7 +33,7 @@
 # RUN: FileCheck %s --input-file=%t-malformed-off-first.err --check-prefix=ALL
 
 ## Don't stop looking for the later unit if non-fatal issues are found.
-# RUN: llvm-dwarfdump -debug-line=0x3c9 %t-malformed.o 2> %t-malformed-off-last.err \
+# RUN: llvm-dwarfdump -debug-line=0x419 %t-malformed.o 2> %t-malformed-off-last.err \
 # RUN:   | FileCheck %s --check-prefix=LAST --implicit-check-not='debug_line[{{.*}}]'
 # RUN: FileCheck %s --input-file=%t-malformed-off-last.err --check-prefix=ALL
 
@@ -243,7 +243,14 @@
 # VERBOSE:       DW_LNE_set_address (0xababcdcdefef0909)
 # VERBOSE-NEXT:  DW_LNE_end_sequence
 
-# LAST:          debug_line[0x000003c9]
+## Table with extended opcode that overruns table end.
+# NONFATAL:      debug_line[0x000003c9]
+# NONFATAL-NEXT: Line table prologue
+# VERBOSE:       DW_LNE_set_address (0x00000000feedfeed)
+# VERBOSE-NEXT:  DW_LNS_copy
+# VERBOSE:       DW_LNE_set_address (0x0000000000000000)
+
+# LAST:          debug_line[0x00000419]
 # VERBOSE:       DW_LNE_set_address (0x00000000cafebabe)
 # VERBOSE-NEXT:  DW_LNE_end_sequence
 
@@ -272,4 +279,6 @@
 # ALL-NEXT: warning: include directories table was not null terminated before the end of the prologue
 # ALL-NEXT: warning: parsing line table prologue at 0x00000390 found an invalid directory or file table description at 0x000003bf
 # ALL-NEXT: warning: file names table was not null terminated before the end of the prologue
+# OTHER-NEXT: warning: unexpected line op length at offset 0x00000411 expected 0x09 found 0x01
+# OTHER-NEXT: warning: last sequence in debug line table at offset 0x000003c9 is not terminated
 # ALL-NOT:  warning: