[DebugInfo] Add check for zero debug line opcode_base

The number of standard opcodes is defined to be opcode_base - 1, so a
value of 0 for the opcode_base caused a crash as an attempt was made to
reserve many entries in a vector. This change fixes the crash, by
issuing a warning and skipping reading of standard opcode lengths in the
event of an opcode_base of 0.

Reviewed by: dblaikie

Differential Revision: https://reviews.llvm.org/D74309

diff --git a/llvm/lib/DebugInfo/DWARF/DWARFDebugLine.cpp b/llvm/lib/DebugInfo/DWARF/DWARFDebugLine.cpp
index 2b4c492..2c869df 100644 (file)
--- a/llvm/lib/DebugInfo/DWARF/DWARFDebugLine.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFDebugLine.cpp
@@ -356,10 +356,21 @@ Error DWARFDebugLine::Prologue::parse(
   LineRange = DebugLineData.getU8(OffsetPtr);
   OpcodeBase = DebugLineData.getU8(OffsetPtr);
 
-  StandardOpcodeLengths.reserve(OpcodeBase - 1);
-  for (uint32_t I = 1; I < OpcodeBase; ++I) {
-    uint8_t OpLen = DebugLineData.getU8(OffsetPtr);
-    StandardOpcodeLengths.push_back(OpLen);
+  if (OpcodeBase == 0) {
+    // If the opcode base is 0, we cannot read the standard opcode lengths (of
+    // which there are supposed to be one fewer than the opcode base). Assume
+    // there are no standard opcodes and continue parsing.
+    RecoverableErrorHandler(createStringError(
+        errc::invalid_argument,
+        "parsing line table prologue at offset 0x%8.8" PRIx64
+        " found opcode base of 0. Assuming no standard opcodes",
+        PrologueOffset));
+  } else {
+    StandardOpcodeLengths.reserve(OpcodeBase - 1);
+    for (uint32_t I = 1; I < OpcodeBase; ++I) {
+      uint8_t OpLen = DebugLineData.getU8(OffsetPtr);
+      StandardOpcodeLengths.push_back(OpLen);
+    }
   }
 
   if (getVersion() >= 5) {

diff --git a/llvm/test/tools/llvm-dwarfdump/X86/Inputs/debug_line_malformed.s b/llvm/test/tools/llvm-dwarfdump/X86/Inputs/debug_line_malformed.s
index e01ed9a..0477a66 100644 (file)
--- a/llvm/test/tools/llvm-dwarfdump/X86/Inputs/debug_line_malformed.s
+++ b/llvm/test/tools/llvm-dwarfdump/X86/Inputs/debug_line_malformed.s
@@ -423,6 +423,30 @@
 .byte   0, 1, 1         # DW_LNE_end_sequence
 .Linvalid_dir_form_end0:
 
+# Zero opcode base.
+.long   .Lzero_opcode_base_end - .Lzero_opcode_base_start # unit length
+.Lzero_opcode_base_start:
+.short  4               # version
+.long   .Lzero_opcode_base_prologue_end-.Lzero_opcode_base_prologue_start # Length of Prologue
+.Lzero_opcode_base_prologue_start:
+.byte   1               # Minimum Instruction Length
+.byte   1               # Maximum Operations per Instruction
+.byte   1               # Default is_stmt
+.byte   0               # Line Base
+.byte   1               # Line Range
+.byte   0               # Opcode Base
+.asciz "dir1"           # Include table
+.byte   0
+.asciz "file1"
+.byte   1, 2, 3
+.byte   0
+.Lzero_opcode_base_prologue_end:
+.byte   0, 9, 2        # DW_LNE_set_address
+.quad   0xffffeeeeddddcccc
+.byte   0x1            # Special opcode
+.byte   0, 1, 1        # DW_LNE_end_sequence
+.Lzero_opcode_base_end:
+
 # Trailing good section.
 .long   .Lunit_good_end - .Lunit_good_start # Length of Unit (DWARF-32 format)
 .Lunit_good_start:

diff --git a/llvm/test/tools/llvm-dwarfdump/X86/debug_line_invalid.test b/llvm/test/tools/llvm-dwarfdump/X86/debug_line_invalid.test
index 60a15b4..d4b5045 100644 (file)
--- a/llvm/test/tools/llvm-dwarfdump/X86/debug_line_invalid.test
+++ b/llvm/test/tools/llvm-dwarfdump/X86/debug_line_invalid.test
@@ -36,7 +36,7 @@
 # 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=0x332 %t-malformed.o 2> %t-malformed-off-last.err \
+# RUN: llvm-dwarfdump -debug-line=0x361 %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
 
@@ -159,7 +159,19 @@
 # NONFATAL-NOT:  file_names
 # NONFATAL:      0xaaaabbbbccccdddd {{.*}} is_stmt end_sequence
 
-# LAST:          debug_line[0x00000332]
+## Opcode base field of value zero.
+# NONFATAL:      debug_line[0x00000332]
+# NONFATAL-NEXT: Line table prologue
+# NONFATAL:      include_directories[  1] = "dir1"
+# NONFATAL-NEXT: file_names[  1]:
+# NONFATAL-NEXT:            name: "file1"
+# NONFATAL-NEXT:       dir_index: 1
+# NONFATAL-NEXT:        mod_time: 0x00000002
+# NONFATAL-NEXT:          length: 0x00000003
+# NONFATAL:      0xffffeeeeddddcccd 1 0 1 0 0 is_stmt{{$}}
+# NONFATAL:      0xffffeeeeddddcccd 1 0 1 0 0 is_stmt end_sequence{{$}}
+
+# LAST:          debug_line[0x00000361]
 # LAST:          0x00000000cafebabe {{.*}} end_sequence
 
 # RESERVED: warning: parsing line table prologue at offset 0x00000048 unsupported reserved unit length found of value 0xfffffffe
@@ -184,4 +196,5 @@
 # ALL-NEXT: warning: parsing line table prologue at 0x000002ae should have ended at 0x000002d9 but it ended at 0x000002e0
 # ALL-NEXT: warning: parsing line table prologue at 0x000002ec found an invalid directory or file table description at 0x00000315
 # ALL-NEXT: warning: failed to parse directory entry because skipping the form value failed.
+# ALL-NEXT: warning: parsing line table prologue at offset 0x00000332 found opcode base of 0. Assuming no standard opcodes
 # ALL-NOT:  warning: