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Kernel: Don't allocate memory for names of processes and threads

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Instead, use the FixedCharBuffer class to ensure we always use a static
buffer storage for these names. This ensures that if a Process or a
Thread were created, there's a guarantee that setting a new name will
never fail, as only copying of strings should be done to that static
storage.

The limits which are set are 32 characters for processes' names and 64
characters for thread names - this is because threads' names could be
more verbose than processes' names.
This commit is contained in:
Liav A 2023-07-17 18:34:19 +03:00 • committed by Andrew Kaster
parent 0d30f558f4
commit 3fd4997fc2
22 changed files with 102 additions and 110 deletions
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25
Kernel/Syscalls/thread.cpp
View file

@ -48,9 +48,9 @@ ErrorOr<FlatPtr> Process::sys$create_thread(void* (*entry)(void*), Userspace<Sys
// We know this thread is not the main_thread,
// So give it a unique name until the user calls $set_thread_name on it
auto new_thread_name = TRY(name().with([&](auto& process_name) {
return KString::formatted("{} [{}]", process_name->view(), thread->tid().value());
return KString::formatted("{} [{}]", process_name.representable_view(), thread->tid().value());
}));
thread->set_name(move(new_thread_name));
thread->set_name(new_thread_name->view());
if (!is_thread_joinable)
thread->detach();
@ -194,17 +194,14 @@ ErrorOr<FlatPtr> Process::sys$set_thread_name(pid_t tid, Userspace<char const*>
VERIFY_NO_PROCESS_BIG_LOCK(this);
TRY(require_promise(Pledge::stdio));
auto name = TRY(try_copy_kstring_from_user(user_name, user_name_length));
const size_t max_thread_name_size = 64;
if (name->length() > max_thread_name_size)
return ENAMETOOLONG;
Thread::Name thread_name {};
TRY(try_copy_name_from_user_into_fixed_string_buffer<64>(user_name, thread_name, user_name_length));
auto thread = Thread::from_tid(tid);
if (!thread || thread->pid() != pid())
return ESRCH;
thread->set_name(move(name));
thread->set_name(thread_name.representable_view());
return 0;
}
@ -220,16 +217,12 @@ ErrorOr<FlatPtr> Process::sys$get_thread_name(pid_t tid, Userspace<char*> buffer
return ESRCH;
TRY(thread->name().with([&](auto& thread_name) -> ErrorOr<void> {
if (thread_name->view().is_null()) {
char null_terminator = '\0';
TRY(copy_to_user(buffer, &null_terminator, sizeof(null_terminator)));
return {};
}
if (thread_name->length() + 1 > buffer_size)
VERIFY(!thread_name.representable_view().is_null());
auto thread_name_view = thread_name.representable_view();
if (thread_name_view.length() + 1 > buffer_size)
return ENAMETOOLONG;
return copy_to_user(buffer, thread_name->characters(), thread_name->length() + 1);
return copy_to_user(buffer, thread_name_view.characters_without_null_termination(), thread_name_view.length() + 1);
}));
return 0;