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Kernel: Fix memory corruption when rolling back regions in execve

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We need to free the regions before reverting the paging scope to the
original one when rolling back changes due to an error. This fixes
silent memory corruption.
This commit is contained in:
Tom 2021-01-01 15:17:23 -07:00 committed by Andreas Kling
parent 2f429bd2d5
commit e87eaf5df0
Notes: sideshowbarker 2024-07-19 00:14:07 +09:00 
Author: https://github.com/tomuta
Commit: https://github.com/SerenityOS/serenity/commit/e87eaf5df01
Pull-request: https://github.com/SerenityOS/serenity/pull/4707
1 changed files with 7 additions and 2 deletions
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9
Kernel/Syscalls/execve.cpp
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@ -157,7 +157,6 @@ KResultOr<Process::LoadResult> Process::load_elf_object(FileDescription& object_
size_t master_tls_alignment = 0;
FlatPtr load_base_address = 0;
MM.enter_process_paging_scope(*this);
String elf_name = object_description.absolute_path();
ASSERT(!Processor::current().in_critical());
@ -293,15 +292,21 @@ KResultOr<Process::LoadResult> Process::load(NonnullRefPtr<FileDescription> main
old_page_directory = move(m_page_directory);
old_regions = move(m_regions);
m_page_directory = page_directory.release_nonnull();
MM.enter_process_paging_scope(*this);
}
ArmedScopeGuard rollback_regions_guard([&]() {
ASSERT(Process::current() == this);
// Need to make sure we don't swap contexts in the middle
ScopedCritical critical;
// Explicitly clear m_regions *before* restoring the page directory,
// otherwise we may silently corrupt memory!
m_regions.clear();
// Now that we freed the regions, revert to the original page directory
// and restore the original regions
m_page_directory = move(old_page_directory);
m_regions = move(old_regions);
MM.enter_process_paging_scope(*this);
m_regions = move(old_regions);
});
if (!interpreter_description) {