[DebugInfo] Don't error for zero-length arange entries

Although the DWARF specification states that .debug_aranges entries
can't have length zero, these can occur in the wild. There's no
particular reason to enforce this part of the spec, since functionally
they have no impact. The patch removes the error and introduces a new
warning for premature terminator entries which does not stop parsing.

Fixes https://bugs.llvm.org/show_bug.cgi?id=46805. See also
https://reviews.llvm.org/D71932 which originally introduced the error.

Reviewed by: ikudrin, dblaikie

Differential Revision: https://reviews.llvm.org/D85313

diff --git a/llvm/include/llvm/DebugInfo/DWARF/DWARFDebugArangeSet.h b/llvm/include/llvm/DebugInfo/DWARF/DWARFDebugArangeSet.h
index 0681a2e..3d5852e 100644 (file)
--- a/llvm/include/llvm/DebugInfo/DWARF/DWARFDebugArangeSet.h
+++ b/llvm/include/llvm/DebugInfo/DWARF/DWARFDebugArangeSet.h
@@ -60,7 +60,8 @@ public:
   DWARFDebugArangeSet() { clear(); }
 
   void clear();
-  Error extract(DWARFDataExtractor data, uint64_t *offset_ptr);
+  Error extract(DWARFDataExtractor data, uint64_t *offset_ptr,
+                function_ref<void(Error)> WarningHandler);
   void dump(raw_ostream &OS) const;
 
   uint64_t getCompileUnitDIEOffset() const { return HeaderData.CuOffset; }

diff --git a/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp b/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp
index bf62194..3bcde8f 100644 (file)
--- a/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp
@@ -502,7 +502,8 @@ void DWARFContext::dump(
                                    0);
     DWARFDebugArangeSet set;
     while (arangesData.isValidOffset(offset)) {
-      if (Error E = set.extract(arangesData, &offset)) {
+      if (Error E =
+              set.extract(arangesData, &offset, DumpOpts.WarningHandler)) {
         RecoverableErrorHandler(std::move(E));
         break;
       }

diff --git a/llvm/lib/DebugInfo/DWARF/DWARFDebugArangeSet.cpp b/llvm/lib/DebugInfo/DWARF/DWARFDebugArangeSet.cpp
index 608fc03..381dd47 100644 (file)
--- a/llvm/lib/DebugInfo/DWARF/DWARFDebugArangeSet.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFDebugArangeSet.cpp
@@ -32,7 +32,8 @@ void DWARFDebugArangeSet::clear() {
 }
 
 Error DWARFDebugArangeSet::extract(DWARFDataExtractor data,
-                                   uint64_t *offset_ptr) {
+                                   uint64_t *offset_ptr,
+                                   function_ref<void(Error)> WarningHandler) {
   assert(data.isValidOffset(*offset_ptr));
   ArangeDescriptors.clear();
   Offset = *offset_ptr;
@@ -132,19 +133,20 @@ Error DWARFDebugArangeSet::extract(DWARFDataExtractor data,
 
   uint64_t end_offset = Offset + full_length;
   while (*offset_ptr < end_offset) {
+    uint64_t EntryOffset = *offset_ptr;
     arangeDescriptor.Address = data.getUnsigned(offset_ptr, HeaderData.AddrSize);
     arangeDescriptor.Length = data.getUnsigned(offset_ptr, HeaderData.AddrSize);
 
-    if (arangeDescriptor.Length == 0) {
-      // Each set of tuples is terminated by a 0 for the address and 0
-      // for the length.
-      if (arangeDescriptor.Address == 0 && *offset_ptr == end_offset)
+    // Each set of tuples is terminated by a 0 for the address and 0
+    // for the length.
+    if (arangeDescriptor.Length == 0 && arangeDescriptor.Address == 0) {
+      if (*offset_ptr == end_offset)
         return ErrorSuccess();
-      return createStringError(
+      WarningHandler(createStringError(
           errc::invalid_argument,
           "address range table at offset 0x%" PRIx64
-          " has an invalid tuple (length = 0) at offset 0x%" PRIx64,
-          Offset, *offset_ptr - tuple_size);
+          " has a premature terminator entry at offset 0x%" PRIx64,
+          Offset, EntryOffset));
     }
 
     ArangeDescriptors.push_back(arangeDescriptor);

diff --git a/llvm/lib/DebugInfo/DWARF/DWARFDebugAranges.cpp b/llvm/lib/DebugInfo/DWARF/DWARFDebugAranges.cpp
index e8ed630..e0db469 100644 (file)
--- a/llvm/lib/DebugInfo/DWARF/DWARFDebugAranges.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFDebugAranges.cpp
@@ -28,7 +28,8 @@ void DWARFDebugAranges::extract(
   DWARFDebugArangeSet Set;
 
   while (DebugArangesData.isValidOffset(Offset)) {
-    if (Error E = Set.extract(DebugArangesData, &Offset)) {
+    if (Error E =
+            Set.extract(DebugArangesData, &Offset, RecoverableErrorHandler)) {
       RecoverableErrorHandler(std::move(E));
       return;
     }

diff --git a/llvm/unittests/DebugInfo/DWARF/DWARFDebugArangeSetTest.cpp b/llvm/unittests/DebugInfo/DWARF/DWARFDebugArangeSetTest.cpp
index 4ec9c5d..face8ec 100644 (file)
--- a/llvm/unittests/DebugInfo/DWARF/DWARFDebugArangeSetTest.cpp
+++ b/llvm/unittests/DebugInfo/DWARF/DWARFDebugArangeSetTest.cpp
@@ -7,12 +7,23 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/DebugInfo/DWARF/DWARFDebugArangeSet.h"
+#include "llvm/Testing/Support/Error.h"
 #include "gtest/gtest.h"
 
 using namespace llvm;
 
 namespace {
 
+struct WarningHandler {
+  ~WarningHandler() { EXPECT_THAT_ERROR(std::move(Err), Succeeded()); }
+
+  void operator()(Error E) { Err = joinErrors(std::move(Err), std::move(E)); }
+
+  Error getWarning() { return std::move(Err); }
+
+  Error Err = Error::success();
+};
+
 template <size_t SecSize>
 void ExpectExtractError(const char (&SecDataRaw)[SecSize],
                         const char *ErrorMessage) {
@@ -21,7 +32,8 @@ void ExpectExtractError(const char (&SecDataRaw)[SecSize],
                                /* AddressSize = */ 4);
   DWARFDebugArangeSet Set;
   uint64_t Offset = 0;
-  Error E = Set.extract(Extractor, &Offset);
+  WarningHandler Warnings;
+  Error E = Set.extract(Extractor, &Offset, Warnings);
   ASSERT_TRUE(E.operator bool());
   EXPECT_STREQ(ErrorMessage, toString(std::move(E)).c_str());
 }
@@ -166,9 +178,9 @@ TEST(DWARFDebugArangeSet, UnevenLength) {
       "of the tuple size");
 }
 
-TEST(DWARFDebugArangeSet, ZeroLengthEntry) {
+TEST(DWARFDebugArangeSet, ZeroAddressEntry) {
   static const char DebugArangesSecRaw[] =
-      "\x24\x00\x00\x00" // Length
+      "\x1c\x00\x00\x00" // Length
       "\x02\x00"         // Version
       "\x00\x00\x00\x00" // Debug Info Offset
       "\x04"             // Address Size
@@ -176,14 +188,84 @@ TEST(DWARFDebugArangeSet, ZeroLengthEntry) {
       "\x00\x00\x00\x00" // Padding
       "\x00\x00\x00\x00" // Entry1: Address
       "\x01\x00\x00\x00" //         Length
+      "\x00\x00\x00\x00" // Termination tuple
+      "\x00\x00\x00\x00";
+  DWARFDataExtractor Extractor(
+      StringRef(DebugArangesSecRaw, sizeof(DebugArangesSecRaw) - 1),
+      /*IsLittleEndian=*/true,
+      /*AddressSize=*/4);
+  DWARFDebugArangeSet Set;
+  uint64_t Offset = 0;
+  ASSERT_THAT_ERROR(Set.extract(Extractor, &Offset, WarningHandler()),
+                    Succeeded());
+  auto Range = Set.descriptors();
+  auto Iter = Range.begin();
+  ASSERT_EQ(std::distance(Iter, Range.end()), 1u);
+  EXPECT_EQ(Iter->Address, 0u);
+  EXPECT_EQ(Iter->Length, 1u);
+}
+
+TEST(DWARFDebugArangeSet, ZeroLengthEntry) {
+  static const char DebugArangesSecRaw[] =
+      "\x1c\x00\x00\x00" // Length
+      "\x02\x00"         // Version
+      "\x00\x00\x00\x00" // Debug Info Offset
+      "\x04"             // Address Size
+      "\x00"             // Segment Selector Size
+      "\x00\x00\x00\x00" // Padding
+      "\x01\x00\x00\x00" // Entry1: Address
+      "\x00\x00\x00\x00" //         Length
+      "\x00\x00\x00\x00" // Termination tuple
+      "\x00\x00\x00\x00";
+  DWARFDataExtractor Extractor(
+      StringRef(DebugArangesSecRaw, sizeof(DebugArangesSecRaw) - 1),
+      /*IsLittleEndian=*/true,
+      /*AddressSize=*/4);
+  DWARFDebugArangeSet Set;
+  uint64_t Offset = 0;
+  ASSERT_THAT_ERROR(Set.extract(Extractor, &Offset, WarningHandler()),
+                    Succeeded());
+  auto Range = Set.descriptors();
+  auto Iter = Range.begin();
+  ASSERT_EQ(std::distance(Iter, Range.end()), 1u);
+  EXPECT_EQ(Iter->Address, 1u);
+  EXPECT_EQ(Iter->Length, 0u);
+}
+
+TEST(DWARFDebugArangesSet, PrematureTerminator) {
+  static const char DebugArangesSecRaw[] =
+      "\x24\x00\x00\x00" // Length
+      "\x02\x00"         // Version
+      "\x00\x00\x00\x00" // Debug Info Offset
+      "\x04"             // Address Size
+      "\x00"             // Segment Selector Size
+      "\x00\x00\x00\x00" // Padding
+      "\x00\x00\x00\x00" // Entry1: Premature
+      "\x00\x00\x00\x00" //         terminator
       "\x01\x00\x00\x00" // Entry2: Address
-      "\x00\x00\x00\x00" //         Length (invalid)
+      "\x01\x00\x00\x00" //         Length
       "\x00\x00\x00\x00" // Termination tuple
       "\x00\x00\x00\x00";
-  ExpectExtractError(
-      DebugArangesSecRaw,
-      "address range table at offset 0x0 has an invalid tuple (length = 0) "
-      "at offset 0x18");
+  DWARFDataExtractor Extractor(
+      StringRef(DebugArangesSecRaw, sizeof(DebugArangesSecRaw) - 1),
+      /*IsLittleEndian=*/true,
+      /*AddressSize=*/4);
+  DWARFDebugArangeSet Set;
+  uint64_t Offset = 0;
+  WarningHandler Warnings;
+  ASSERT_THAT_ERROR(Set.extract(Extractor, &Offset, Warnings), Succeeded());
+  auto Range = Set.descriptors();
+  auto Iter = Range.begin();
+  ASSERT_EQ(std::distance(Iter, Range.end()), 2u);
+  EXPECT_EQ(Iter->Address, 0u);
+  EXPECT_EQ(Iter->Length, 0u);
+  ++Iter;
+  EXPECT_EQ(Iter->Address, 1u);
+  EXPECT_EQ(Iter->Length, 1u);
+  EXPECT_THAT_ERROR(
+      Warnings.getWarning(),
+      FailedWithMessage("address range table at offset 0x0 has a premature "
+                        "terminator entry at offset 0x10"));
 }
 
 } // end anonymous namespace