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LibELF: Add methods to validate the ELF and program headers

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These will make sure there's no funny business or funny offsets in the
main ELF header or each Program Header. More can still be done (like
validating section headers), but this is a good start
This commit is contained in:
Andrew Kaster 2020-01-10 18:25:12 -07:00 • committed by Andreas Kling
parent fe0eb04a22
commit 046d6a6bbb
3 changed files with 181 additions and 5 deletions
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11
Libraries/LibELF/ELFLoader.cpp
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@ -78,7 +78,16 @@ bool ELFLoader::layout()
failed = true;
return;
}
do_memcpy(program_header.vaddr().as_ptr(), program_header.raw_data(), program_header.size_in_image());
// It's not always the case with PIE executables (and very well shouldn't be) that the
// virtual address in the program header matches the one we end up giving the process.
// In order to copy the data image correctly into memory, we need to copy the data starting at
// the right initial page offset into the pages allocated for the elf_alloc-XX section.
// FIXME: There's an opportunity to munmap, or at least mprotect, the padding space between
// the .text and .data PT_LOAD sections of the executable.
// Accessing it would definitely be a bug.
auto page_offset = program_header.vaddr();
page_offset.mask(~PAGE_MASK);
do_memcpy((u8*)allocated_section + page_offset.get(), program_header.raw_data(), program_header.size_in_image());
} else {
auto* mapped_section = map_section_hook(
program_header.vaddr(),