[PATCH] D32987: DWARF: When parsing type unit headers take the length field into account.
Wolfgang Pieb via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Tue May 9 12:51:58 PDT 2017
This revision was automatically updated to reflect the committed changes.
Closed by commit rL302574: [DWARF] Fix a parsing issue with type unit headers. (authored by wolfgangp).
Changed prior to commit:
https://reviews.llvm.org/D32987?vs=98238&id=98341#toc
Repository:
rL LLVM
https://reviews.llvm.org/D32987
Files:
llvm/trunk/lib/DebugInfo/DWARF/DWARFTypeUnit.cpp
llvm/trunk/test/DebugInfo/Inputs/typeunit-header.elf-x86-64
llvm/trunk/test/DebugInfo/Inputs/typeunit-header.s
llvm/trunk/test/DebugInfo/typeunit-header.test
Index: llvm/trunk/test/DebugInfo/typeunit-header.test
===================================================================
--- llvm/trunk/test/DebugInfo/typeunit-header.test
+++ llvm/trunk/test/DebugInfo/typeunit-header.test
@@ -0,0 +1,15 @@
+RUN: llvm-dwarfdump %p/Inputs/typeunit-header.elf-x86-64 | FileCheck %s
+
+This is testing a bugfix where parsing the type unit header was not
+taking the unit's intial length field into account when validating.
+
+The input file is hand-coded assembler to generate a type unit stub,
+which only contains a type unit DIE with a sole visibility attribute.
+
+We make sure that llvm-dwarfdump is parsing the type unit header correctly
+and displays it.
+
+CHECK: .debug_types contents:
+CHECK: 0x00000000: Type Unit: length = 0x00000019 version = 0x0004 abbr_offset = 0x0000 addr_size = 0x08 name = '' type_signature = 0x0011223344556677 type_offset = 0x0019 (next unit at 0x0000001d)
+CHECK: 0x00000017: DW_TAG_type_unit [1] *
+CHECK: DW_AT_visibility [DW_FORM_data1] (DW_VIS_local)
Index: llvm/trunk/test/DebugInfo/Inputs/typeunit-header.s
===================================================================
--- llvm/trunk/test/DebugInfo/Inputs/typeunit-header.s
+++ llvm/trunk/test/DebugInfo/Inputs/typeunit-header.s
@@ -0,0 +1,49 @@
+# Test object with an artifically constructed type unit header to verify
+# that the length field is correctly used to verify the validity of the
+# type_offset field.
+#
+# To generate the test object:
+# llvm-mc -triple x86_64-unknown-linux typeunit-header.s -filetype=obj \
+# -o typeunit-header.elf-x86-64
+#
+# We only have an abbreviation for the type unit die which is all we need.
+# Real type unit dies have quite different attributes of course, but we
+# just need to demonstrate an issue with validating length, so we just give it
+# a single visibility attribute.
+ .section .debug_abbrev,"", at progbits
+ .byte 0x01 # Abbrev code
+ .byte 0x41 # DW_TAG_type_unit
+ .byte 0x01 # DW_CHILDREN_yes
+ .byte 0x17 # DW_AT_visibility
+ .byte 0x0b # DW_FORM_data1
+ .byte 0x00 # EOM(1)
+ .byte 0x00 # EOM(2)
+ .byte 0x02 # Abbrev code
+ .byte 0x13 # DW_TAG_structure_type
+ .byte 0x00 # DW_CHILDREN_no (no members)
+ .byte 0x17 # DW_AT_visibility
+ .byte 0x0b # DW_FORM_data1
+ .byte 0x00 # EOM(1)
+ .byte 0x00 # EOM(2)
+ .byte 0x00 # EOM(3)
+
+ .section .debug_types,"", at progbits
+# DWARF v4 Type unit header - DWARF32 format.
+TU_4_32_start:
+ .long TU_4_32_end-TU_4_32_version # Length of Unit
+TU_4_32_version:
+ .short 4 # DWARF version number
+ .long .debug_abbrev # Offset Into Abbrev. Section
+ .byte 8 # Address Size (in bytes)
+ .quad 0x0011223344556677 # Type Signature
+ .long TU_4_32_type-TU_4_32_start # Type offset
+# The type-unit DIE, which has just a visibility attribute.
+ .byte 1 # Abbreviation code
+ .byte 1 # DW_VIS_local
+# The type DIE, which also just has a one-byte visibility attribute.
+TU_4_32_type:
+ .byte 2 # Abbreviation code
+ .byte 1 # DW_VIS_local
+ .byte 0 # NULL
+ .byte 0 # NULL
+TU_4_32_end:
Index: llvm/trunk/lib/DebugInfo/DWARF/DWARFTypeUnit.cpp
===================================================================
--- llvm/trunk/lib/DebugInfo/DWARF/DWARFTypeUnit.cpp
+++ llvm/trunk/lib/DebugInfo/DWARF/DWARFTypeUnit.cpp
@@ -24,7 +24,11 @@
return false;
TypeHash = debug_info.getU64(offset_ptr);
TypeOffset = debug_info.getU32(offset_ptr);
- return TypeOffset < getLength();
+ // TypeOffset is relative to the beginning of the header,
+ // so we have to account for the leading length field.
+ // FIXME: The size of the length field is 12 in DWARF64.
+ unsigned SizeOfLength = 4;
+ return TypeOffset < getLength() + SizeOfLength;
}
void DWARFTypeUnit::dump(raw_ostream &OS, bool SummarizeTypes) {
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