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Kernel: Limit exec arguments and environment to 1/8th of stack each

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This sort-of matches what some other systems do and seems like a
generally sane thing to do instead of allowing programs to spawn a
child with a nearly full stack.
This commit is contained in:
Andreas Kling 2021-01-17 18:26:12 +01:00
parent 6613cef2f8
commit 992f513ad2
1 changed files with 19 additions and 7 deletions
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26
Kernel/Syscalls/execve.cpp
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@ -52,16 +52,28 @@ static Vector<ELF::AuxiliaryValue> generate_auxiliary_vector(FlatPtr load_base,
static bool validate_stack_size(const Vector<String>& arguments, const Vector<String>& environment)
{
size_t total_blob_size = 0;
for (auto& a : arguments)
total_blob_size += a.length() + 1;
for (auto& e : environment)
total_blob_size += e.length() + 1;
size_t total_arguments_size = 0;
size_t total_environment_size = 0;
size_t total_meta_size = sizeof(char*) * (arguments.size() + 1) + sizeof(char*) * (environment.size() + 1);
for (auto& a : arguments)
total_arguments_size += a.length() + 1;
for (auto& e : environment)
total_environment_size += e.length() + 1;
total_arguments_size += sizeof(char*) * (arguments.size() + 1);
total_environment_size += sizeof(char*) * (environment.size() + 1);
static constexpr size_t max_arguments_size = Thread::default_userspace_stack_size / 8;
static constexpr size_t max_environment_size = Thread::default_userspace_stack_size / 8;
if (total_arguments_size > max_arguments_size)
return false;
if (total_environment_size > max_environment_size)
return false;
// FIXME: This doesn't account for the size of the auxiliary vector
return (total_blob_size + total_meta_size) < Thread::default_userspace_stack_size;
return true;
}
static KResultOr<FlatPtr> make_userspace_stack_for_main_thread(Region& region, Vector<String> arguments, Vector<String> environment, Vector<ELF::AuxiliaryValue> auxiliary_values)