Skip to content

fix: replace UserPtr with starry-vm in sys_clone #97

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
AsakuraMizu wants to merge 1 commit into
base: main
Choose a base branch
from
Open

fix: replace UserPtr with starry-vm in sys_clone #97

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
10 changes: 5 additions & 5 deletions api/src/syscall/task/clone.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -13,10 +13,10 @@ use starry_core::{
};
use starry_process::Pid;
use starry_signal::Signo;
use starry_vm::VmMutPtr;

use crate::{
file::{FD_TABLE, FileLike, PidFd},
mm::UserPtr,
task::new_user_task,
};

Expand Down Expand Up @@ -128,9 +128,9 @@ pub fn sys_clone(
new_uctx.set_retval(0);

let set_child_tid = if flags.contains(CloneFlags::CHILD_SETTID) {
Some(UserPtr::<u32>::from(child_tid).get_as_mut()?)
child_tid
} else {
None
0
};

let curr = current();
Expand All @@ -140,7 +140,7 @@ pub fn sys_clone(

let tid = new_task.id().as_u64() as Pid;
if flags.contains(CloneFlags::PARENT_SETTID) {
*UserPtr::<Pid>::from(parent_tid).get_as_mut()? = tid;
(parent_tid as *mut Pid).vm_write(tid)?;
}

let new_proc_data = if flags.contains(CloneFlags::THREAD) {
Expand Down Expand Up @@ -214,7 +214,7 @@ pub fn sys_clone(

if flags.contains(CloneFlags::PIDFD) {
let pidfd = PidFd::new(&new_proc_data);
*UserPtr::<i32>::from(parent_tid).get_as_mut()? = pidfd.add_to_fd_table(true)?;
(parent_tid as *mut i32).vm_write(pidfd.add_to_fd_table(true)?)?;
}

let thr = Thread::new(tid, new_proc_data);
Expand Down
15 changes: 4 additions & 11 deletions api/src/task.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,6 @@ use bytemuck::AnyBitPattern;
use linux_raw_sys::general::ROBUST_LIST_LIMIT;
use starry_core::{
futex::FutexKey,
mm::access_user_memory,
shm::SHM_MANAGER,
task::{
AsThread, get_process_data, get_task, send_signal_to_process, send_signal_to_thread,
Expand All @@ -25,20 +24,14 @@ use crate::{
};

/// Create a new user task.
pub fn new_user_task(
name: &str,
mut uctx: UserContext,
set_child_tid: Option<&'static mut Pid>,
) -> TaskInner {
pub fn new_user_task(name: &str, mut uctx: UserContext, set_child_tid: usize) -> TaskInner {
TaskInner::new(
move || {
let curr = axtask::current();

access_user_memory(|| {
if let Some(tid) = set_child_tid {
*tid = curr.id().as_u64() as Pid;
}
});
if let Some(tid) = (set_child_tid as *mut Pid).nullable() {
tid.vm_write(curr.id().as_u64() as Pid).ok();
Copy link

Copilot AI Dec 24, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Silently discarding vm_write errors with .ok() may lead to unexpected behavior. If set_child_tid points to an invalid address, the old code (which used direct pointer dereference within access_user_memory) would trigger a page fault that could terminate the task. The new code silently ignores write failures, allowing the task to continue. Consider handling errors by at least logging them, or by raising a signal similar to how line 162 in do_exit checks is_ok() but takes conditional action based on the result.

Suggested change
tid.vm_write(curr.id().as_u64() as Pid).ok();
if let Err(err) = tid.vm_write(curr.id().as_u64() as Pid) {
warn!(
"Failed to write child TID to user memory at {:p}: {:?}",
tid.as_ptr(),
err
);
// Mirror the behavior for serious memory faults by raising SIGSEGV.
raise_signal_fatal(SignalInfo::new_kernel(Signo::SIGSEGV))
.expect("Failed to send SIGSEGV");
}

Copilot uses AI. Check for mistakes.
}

info!("Enter user space: ip={:#x}, sp={:#x}", uctx.ip(), uctx.sp());

Expand Down
2 changes: 1 addition & 1 deletion src/entry.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -36,7 +36,7 @@ pub fn run_initproc(args: &[String], envs: &[String]) -> i32 {

let uctx = UserContext::new(entry_vaddr.into(), ustack_top, 0);

let mut task = new_user_task(name, uctx, None);
let mut task = new_user_task(name, uctx, 0);
task.ctx_mut().set_page_table_root(uspace.page_table_root());

let pid = task.id().as_u64() as Pid;
Expand Down