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LibELF: Randomize the VM reservation (so we don't break ASLR)

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This commit is contained in:
Andreas Kling 2021-02-03 23:56:42 +01:00
parent 3a3270eb68
commit 349cf6ad67
1 changed files with 5 additions and 6 deletions
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11
Userland/Libraries/LibELF/DynamicLoader.cpp
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@ -277,12 +277,11 @@ void DynamicLoader::load_program_headers()
// Process regions in order: .text, .data, .tls // Process regions in order: .text, .data, .tls
void* requested_load_address = m_elf_image.is_dynamic() ? nullptr : text_region.value().desired_load_address().as_ptr(); void* requested_load_address = m_elf_image.is_dynamic() ? nullptr : text_region.value().desired_load_address().as_ptr();
int text_mmap_flags = MAP_SHARED; int reservation_mmap_flags = MAP_ANON | MAP_PRIVATE | MAP_NORESERVE;
if (m_elf_image.is_dynamic()) if (m_elf_image.is_dynamic())
text_mmap_flags |= MAP_RANDOMIZED; reservation_mmap_flags |= MAP_RANDOMIZED;
else else
text_mmap_flags |= MAP_FIXED; reservation_mmap_flags |= MAP_FIXED;
ASSERT(!text_region.value().is_writable()); ASSERT(!text_region.value().is_writable());
@ -294,7 +293,7 @@ void DynamicLoader::load_program_headers()
total_mapping_size += data_region.value().required_load_size(); total_mapping_size += data_region.value().required_load_size();
ASSERT(!total_mapping_size.has_overflow()); ASSERT(!total_mapping_size.has_overflow());
auto* reservation = mmap(requested_load_address, total_mapping_size.value(), PROT_NONE, MAP_ANON | MAP_PRIVATE | MAP_NORESERVE, 0, 0); auto* reservation = mmap(requested_load_address, total_mapping_size.value(), PROT_NONE, reservation_mmap_flags, 0, 0);
if (reservation == MAP_FAILED) { if (reservation == MAP_FAILED) {
perror("mmap reservation"); perror("mmap reservation");
ASSERT_NOT_REACHED(); ASSERT_NOT_REACHED();
@ -311,7 +310,7 @@ void DynamicLoader::load_program_headers()
reservation, reservation,
text_region.value().required_load_size(), text_region.value().required_load_size(),
PROT_READ, PROT_READ,
text_mmap_flags, MAP_FILE | MAP_SHARED | MAP_FIXED,
m_image_fd, m_image_fd,
text_region.value().offset(), text_region.value().offset(),
String::formatted("{}: .text", m_filename).characters()); String::formatted("{}: .text", m_filename).characters());