LibDebug+LibCoredump: Use ByteReader to do unaligned reads

The previous solution of "lol whats a UB" was not nice and tripped over
itself when it was run under UBSAN, fix this by doing explicit
byte-by-byte reads where needed.

2 files changed, 13 insertions, 9 deletions

diff --git a/Userland/Libraries/LibDebug/Dwarf/CompilationUnit.cpp b/Userland/Libraries/LibDebug/Dwarf/CompilationUnit.cpp
index d8b0343d76..9bef566e5a 100644
--- a/Userland/Libraries/LibDebug/Dwarf/CompilationUnit.cpp
+++ b/Userland/Libraries/LibDebug/Dwarf/CompilationUnit.cpp
@@ -6,6 +6,7 @@
 
 #include "CompilationUnit.h"
 #include "DIE.h"
+#include <AK/ByteReader.h>
 
 namespace Debug::Dwarf {
 
@@ -94,9 +95,11 @@ FlatPtr CompilationUnit::get_address(size_t index) const
     auto base = address_table_base();
     auto debug_addr_data = dwarf_info().debug_addr_data();
     VERIFY(base < debug_addr_data.size());
-    auto addresses = reinterpret_cast<FlatPtr const*>(debug_addr_data.offset(base));
-    VERIFY(base + index * sizeof(FlatPtr) < debug_addr_data.size());
-    return addresses[index];
+    auto addresses = debug_addr_data.slice(base);
+    VERIFY(index * sizeof(FlatPtr) < addresses.size());
+    FlatPtr value { 0 };
+    ByteReader::load<FlatPtr>(addresses.offset_pointer(index * sizeof(FlatPtr)), value);
+    return value;
 }
 
 char const* CompilationUnit::get_string(size_t index) const
@@ -105,9 +108,9 @@ char const* CompilationUnit::get_string(size_t index) const
     auto debug_str_offsets_data = dwarf_info().debug_str_offsets_data();
     VERIFY(base < debug_str_offsets_data.size());
     // FIXME: This assumes DWARF32
-    auto offsets = reinterpret_cast<u32 const*>(debug_str_offsets_data.offset(base));
-    VERIFY(base + index * sizeof(u32) < debug_str_offsets_data.size());
-    auto offset = offsets[index];
-    return reinterpret_cast<char const*>(dwarf_info().debug_strings_data().offset(offset));
+    auto offsets = debug_str_offsets_data.slice(base);
+    VERIFY(index * sizeof(u32) < offsets.size());
+    auto offset = ByteReader::load32(offsets.offset_pointer(index * sizeof(u32)));
+    return bit_cast<char const*>(dwarf_info().debug_strings_data().offset(offset));
 }
 }
diff --git a/Userland/Libraries/LibDebug/Dwarf/DwarfInfo.cpp b/Userland/Libraries/LibDebug/Dwarf/DwarfInfo.cpp
index da94efe54b..14cec259bd 100644
--- a/Userland/Libraries/LibDebug/Dwarf/DwarfInfo.cpp
+++ b/Userland/Libraries/LibDebug/Dwarf/DwarfInfo.cpp
@@ -9,6 +9,7 @@
 #include "AttributeValue.h"
 #include "CompilationUnit.h"
 
+#include <AK/ByteReader.h>
 #include <AK/MemoryStream.h>
 #include <LibDebug/DebugInfo.h>
 
@@ -344,8 +345,8 @@ void DwarfInfo::build_cached_dies() const
                 auto index = ranges->as_unsigned();
                 auto base = die.compilation_unit().range_lists_base();
                 // FIXME: This assumes that the format is DWARf32
-                auto offsets = reinterpret_cast<u32 const*>(debug_range_lists_data().offset(base));
-                offset = offsets[index] + base;
+                auto offsets = debug_range_lists_data().slice(base);
+                offset = ByteReader::load32(offsets.offset_pointer(index * sizeof(u32))) + base;
             }
 
             Vector<DIERange> entries;