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LibJS: Seal Bytecode Blocks and munmap them (#7919)

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This commit is contained in:
Leon Albrecht 2021-06-08 17:21:48 +02:00 • committed by GitHub
parent 064ed8279e
commit c6ce7c9326
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2 changed files with 19 additions and 5 deletions
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20
Userland/Libraries/LibJS/Bytecode/Block.cpp
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@ -28,19 +28,31 @@ Block::Block()
Block::~Block()
{
unseal();
Bytecode::InstructionStreamIterator it(instruction_stream());
while (!it.at_end()) {
auto& to_destroy = (*it);
++it;
Instruction::destroy(const_cast<Instruction&>(to_destroy));
}
munmap(m_buffer, m_buffer_capacity);
}
void Block::seal()
void Block::seal() const
{
// FIXME: mprotect the instruction stream as PROT_READ
// This is currently not possible because instructions can have destructors (that clean up strings)
// Instructions should instead be destructor-less and refer to strings in a string table on the Bytecode::Block.
if (mprotect(m_buffer, m_buffer_capacity, PROT_READ) < 0) {
perror("ByteCode::Block::seal: mprotect");
VERIFY_NOT_REACHED();
}
}
void Block::unseal()
{
if (mprotect(m_buffer, m_buffer_capacity, PROT_READ | PROT_WRITE) < 0) {
perror("ByteCode::Block::unseal: mprotect");
VERIFY_NOT_REACHED();
}
}
void Block::dump() const

4
Userland/Libraries/LibJS/Bytecode/Block.h
View file

@ -42,7 +42,9 @@ public:
static NonnullOwnPtr<Block> create();
~Block();
void seal();
void seal() const;
void unseal();
void dump() const;
ReadonlyBytes instruction_stream() const { return ReadonlyBytes { m_buffer, m_buffer_size }; }