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Kernel+LibC+LibELF: Set stack size based on PT_GNU_STACK during execve

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Some programs explicitly ask for a different initial stack size than
what the OS provides. This is implemented in ELF by having a
PT_GNU_STACK header which has its p_memsz set to the amount that the
program requires. This commit implements this policy by reading the
p_memsz of the header and setting the main thread stack size to that.
ELF::Image::validate_program_headers ensures that the size attribute is
a reasonable value.
This commit is contained in:
sin-ack 2022-10-01 19:29:59 +00:00 • committed by Andrew Kaster
parent 3275015786
commit ef6921d7c7
9 changed files with 43 additions and 7 deletions
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11
Kernel/Syscalls/execve.cpp
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@ -279,6 +279,7 @@ static ErrorOr<LoadResult> load_elf_object(NonnullOwnPtr<Memory::AddressSpace> n
size_t master_tls_size = 0;
size_t master_tls_alignment = 0;
FlatPtr load_base_address = 0;
size_t stack_size = 0;
auto elf_name = TRY(object_description.pseudo_path());
VERIFY(!Processor::in_critical());
@ -374,6 +375,10 @@ static ErrorOr<LoadResult> load_elf_object(NonnullOwnPtr<Memory::AddressSpace> n
if (program_header.type() == PT_LOAD)
return load_section(program_header);
if (program_header.type() == PT_GNU_STACK) {
stack_size = program_header.size_in_memory();
}
// NOTE: We ignore other program header types.
return {};
};
@ -387,12 +392,16 @@ static ErrorOr<LoadResult> load_elf_object(NonnullOwnPtr<Memory::AddressSpace> n
return result;
}());
if (stack_size == 0) {
stack_size = Thread::default_userspace_stack_size;
}
if (!elf_image.entry().offset(load_offset).get()) {
dbgln("do_exec: Failure loading program, entry pointer is invalid! {})", elf_image.entry().offset(load_offset));
return ENOEXEC;
}
auto* stack_region = TRY(new_space->allocate_region(Memory::RandomizeVirtualAddress::Yes, {}, Thread::default_userspace_stack_size, PAGE_SIZE, "Stack (Main thread)"sv, PROT_READ | PROT_WRITE, AllocationStrategy::Reserve));
auto* stack_region = TRY(new_space->allocate_region(Memory::RandomizeVirtualAddress::Yes, {}, stack_size, PAGE_SIZE, "Stack (Main thread)"sv, PROT_READ | PROT_WRITE, AllocationStrategy::Reserve));
stack_region->set_stack(true);
return LoadResult {