[lldb][llvm] Return an error instead of crashing when parsing a line table prologue. (#80769)

We recently ran into some bad DWARF where the `DW_AT_stmt_list` of many
compile units was randomly set to invalid values and was causing LLDB to
crash due to an assertion about address sizes not matching. Instead of
asserting, we should return an appropriate recoverable `llvm::Error`.

Author: clayborg

llvm/lib/DebugInfo/DWARF/DWARFDebugLine.cpp

@@ -389,9 +389,25 @@ Error DWARFDebugLine::Prologue::parse(
 
   if (getVersion() >= 5) {
     FormParams.AddrSize = DebugLineData.getU8(Cursor);
-    assert((!Cursor || DebugLineData.getAddressSize() == 0 ||
-            DebugLineData.getAddressSize() == getAddressSize()) &&
-           "Line table header and data extractor disagree");
+    const uint8_t DataAddrSize = DebugLineData.getAddressSize();
+    const uint8_t PrologueAddrSize = getAddressSize();
+    if (Cursor) {
+      if (DataAddrSize == 0) {
+        if (PrologueAddrSize != 4 && PrologueAddrSize != 8) {
+          RecoverableErrorHandler(createStringError(
+              errc::not_supported,
+              "parsing line table prologue at offset 0x%8.8" PRIx64
+              ": invalid address size %" PRIu8,
+              PrologueOffset, PrologueAddrSize));
+        }
+      } else if (DataAddrSize != PrologueAddrSize) {
+        RecoverableErrorHandler(createStringError(
+            errc::not_supported,
+            "parsing line table prologue at offset 0x%8.8" PRIx64 ": address "
+            "size %" PRIu8 " doesn't match architecture address size %" PRIu8,
+            PrologueOffset, PrologueAddrSize, DataAddrSize));
+      }
+    }
     SegSelectorSize = DebugLineData.getU8(Cursor);
   }
 

llvm/unittests/DebugInfo/DWARF/DWARFDebugLineTest.cpp

@@ -823,7 +823,9 @@ TEST_F(DebugLineBasicFixture, ErrorForUnsupportedAddressSizeDefinedInHeader) {
                                                     nullptr, RecordRecoverable);
   EXPECT_THAT_ERROR(
       std::move(Recoverable),
-      FailedWithMessage("address size 0x09 of DW_LNE_set_address opcode at "
+      FailedWithMessage("parsing line table prologue at offset 0x00000000: "
+                        "invalid address size 9",
+                        "address size 0x09 of DW_LNE_set_address opcode at "
                         "offset 0x00000038 is unsupported"));
   ASSERT_THAT_EXPECTED(ExpectedLineTable, Succeeded());
   ASSERT_EQ((*ExpectedLineTable)->Rows.size(), 3u);