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LibDebug+LibCoredump: Use ByteReader to do unaligned reads

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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.
This commit is contained in:
Ali Mohammad Pur 2022-01-27 13:22:45 +03:30 • committed by Linus Groh
parent 6d64b13a1b
commit da3c4e5df5
3 changed files with 18 additions and 11 deletions
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7
Userland/Libraries/LibCoredump/Reader.cpp
View file

@ -4,6 +4,7 @@
* SPDX-License-Identifier: BSD-2-Clause * SPDX-License-Identifier: BSD-2-Clause
*/ */
#include <AK/ByteReader.h>
#include <AK/HashTable.h> #include <AK/HashTable.h>
#include <AK/JsonObject.h> #include <AK/JsonObject.h>
#include <AK/JsonValue.h> #include <AK/JsonValue.h>
@ -139,8 +140,10 @@ Optional<FlatPtr> Reader::peek_memory(FlatPtr address) const
return {}; return {};
FlatPtr offset_in_region = address - region->region_start; FlatPtr offset_in_region = address - region->region_start;
const char* region_data = image().program_header(region->program_header_index).raw_data(); auto* region_data = bit_cast<const u8*>(image().program_header(region->program_header_index).raw_data());
return *(const FlatPtr*)(&region_data[offset_in_region]); FlatPtr value { 0 };
ByteReader::load(region_data + offset_in_region, value);
return value;
} }
const JsonObject Reader::process_info() const const JsonObject Reader::process_info() const

17
Userland/Libraries/LibDebug/Dwarf/CompilationUnit.cpp
View file

@ -6,6 +6,7 @@
#include "CompilationUnit.h" #include "CompilationUnit.h"
#include "DIE.h" #include "DIE.h"
#include <AK/ByteReader.h>
namespace Debug::Dwarf { namespace Debug::Dwarf {
@ -94,9 +95,11 @@ FlatPtr CompilationUnit::get_address(size_t index) const
auto base = address_table_base(); auto base = address_table_base();
auto debug_addr_data = dwarf_info().debug_addr_data(); auto debug_addr_data = dwarf_info().debug_addr_data();
VERIFY(base < debug_addr_data.size()); VERIFY(base < debug_addr_data.size());
auto addresses = reinterpret_cast<FlatPtr const*>(debug_addr_data.offset(base)); auto addresses = debug_addr_data.slice(base);
VERIFY(base + index * sizeof(FlatPtr) < debug_addr_data.size()); VERIFY(index * sizeof(FlatPtr) < addresses.size());
return addresses[index]; FlatPtr value { 0 };
ByteReader::load<FlatPtr>(addresses.offset_pointer(index * sizeof(FlatPtr)), value);
return value;
} }
char const* CompilationUnit::get_string(size_t index) const 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(); auto debug_str_offsets_data = dwarf_info().debug_str_offsets_data();
VERIFY(base < debug_str_offsets_data.size()); VERIFY(base < debug_str_offsets_data.size());
// FIXME: This assumes DWARF32 // FIXME: This assumes DWARF32
auto offsets = reinterpret_cast<u32 const*>(debug_str_offsets_data.offset(base)); auto offsets = debug_str_offsets_data.slice(base);
VERIFY(base + index * sizeof(u32) < debug_str_offsets_data.size()); VERIFY(index * sizeof(u32) < offsets.size());
auto offset = offsets[index]; auto offset = ByteReader::load32(offsets.offset_pointer(index * sizeof(u32)));
return reinterpret_cast<char const*>(dwarf_info().debug_strings_data().offset(offset)); return bit_cast<char const*>(dwarf_info().debug_strings_data().offset(offset));
} }
} }

5
Userland/Libraries/LibDebug/Dwarf/DwarfInfo.cpp
View file

@ -9,6 +9,7 @@
#include "AttributeValue.h" #include "AttributeValue.h"
#include "CompilationUnit.h" #include "CompilationUnit.h"
#include <AK/ByteReader.h>
#include <AK/MemoryStream.h> #include <AK/MemoryStream.h>
#include <LibDebug/DebugInfo.h> #include <LibDebug/DebugInfo.h>
@ -344,8 +345,8 @@ void DwarfInfo::build_cached_dies() const
auto index = ranges->as_unsigned(); auto index = ranges->as_unsigned();
auto base = die.compilation_unit().range_lists_base(); auto base = die.compilation_unit().range_lists_base();
// FIXME: This assumes that the format is DWARf32 // FIXME: This assumes that the format is DWARf32
auto offsets = reinterpret_cast<u32 const*>(debug_range_lists_data().offset(base)); auto offsets = debug_range_lists_data().slice(base);
offset = offsets[index] + base; offset = ByteReader::load32(offsets.offset_pointer(index * sizeof(u32))) + base;
} }
Vector<DIERange> entries; Vector<DIERange> entries;