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[DWARF parser] Make DWARF parser more robust against missing compile/type units.

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DWARF standard claims that each compilation/type unit header in
.debug_info/.debug_types section must be followed by corresponding
compile/type unit DIE, possibly with its children. Two situations
are possible:

 * compile/type unit DIE is missing because DWARF producer failed to
   emit it.
 * DWARF parser failed to parse unit DIE correctly, for instance if it
   contains some unsupported attributes (see r237721, for instance).

In either of these cases, the library, and the tools that use it
(llvm-dwarfdump, llvm-symbolizer) should not crash. Insert appropriate
checks to protect against this.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237733 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Alexey Samsonov
2015-05-19 21:54:32 +00:00
parent b9b3fb261e
commit 05f725eb67
6 changed files with 33 additions and 27 deletions
Download Patch File Download Diff File Expand all files Collapse all files

19
lib/DebugInfo/DWARF/DWARFContext.cpp
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@@ -140,9 +140,11 @@ void DWARFContext::dump(raw_ostream &OS, DIDumpType DumpType) {
OS << "\n.debug_line contents:\n";
for (const auto &CU : compile_units()) {
savedAddressByteSize = CU->getAddressByteSize();
unsigned stmtOffset =
CU->getCompileUnitDIE()->getAttributeValueAsSectionOffset(
CU.get(), DW_AT_stmt_list, -1U);
const auto *CUDIE = CU->getUnitDIE();
if (CUDIE == nullptr)
continue;
unsigned stmtOffset = CUDIE->getAttributeValueAsSectionOffset(
CU.get(), DW_AT_stmt_list, -1U);
if (stmtOffset != -1U) {
DataExtractor lineData(getLineSection().Data, isLittleEndian(),
savedAddressByteSize);
@@ -321,13 +323,14 @@ const DWARFDebugFrame *DWARFContext::getDebugFrame() {
}
const DWARFLineTable *
DWARFContext::getLineTableForUnit(DWARFUnit *cu) {
DWARFContext::getLineTableForUnit(DWARFUnit *U) {
if (!Line)
Line.reset(new DWARFDebugLine(&getLineSection().Relocs));
const auto *UnitDIE = U->getUnitDIE();
if (UnitDIE == nullptr)
return nullptr;
unsigned stmtOffset =
cu->getCompileUnitDIE()->getAttributeValueAsSectionOffset(
cu, DW_AT_stmt_list, -1U);
UnitDIE->getAttributeValueAsSectionOffset(U, DW_AT_stmt_list, -1U);
if (stmtOffset == -1U)
return nullptr; // No line table for this compile unit.
@@ -337,7 +340,7 @@ DWARFContext::getLineTableForUnit(DWARFUnit *cu) {
// We have to parse it first.
DataExtractor lineData(getLineSection().Data, isLittleEndian(),
cu->getAddressByteSize());
U->getAddressByteSize());
return Line->getOrParseLineTable(lineData, stmtOffset);
}