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-rw-r--r--kernel/ptrace.c74
1 files changed, 59 insertions, 15 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 1599157..6cbeaae 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -117,11 +117,45 @@ void __ptrace_unlink(struct task_struct *child)
* TASK_KILLABLE sleeps.
*/
if (child->jobctl & JOBCTL_STOP_PENDING || task_is_traced(child))
- signal_wake_up(child, task_is_traced(child));
+ ptrace_signal_wake_up(child, true);
spin_unlock(&child->sighand->siglock);
}
+/* Ensure that nothing can wake it up, even SIGKILL */
+static bool ptrace_freeze_traced(struct task_struct *task)
+{
+ bool ret = false;
+
+ /* Lockless, nobody but us can set this flag */
+ if (task->jobctl & JOBCTL_LISTENING)
+ return ret;
+
+ spin_lock_irq(&task->sighand->siglock);
+ if (task_is_traced(task) && !__fatal_signal_pending(task)) {
+ task->state = __TASK_TRACED;
+ ret = true;
+ }
+ spin_unlock_irq(&task->sighand->siglock);
+
+ return ret;
+}
+
+static void ptrace_unfreeze_traced(struct task_struct *task)
+{
+ if (task->state != __TASK_TRACED)
+ return;
+
+ WARN_ON(!task->ptrace || task->parent != current);
+
+ spin_lock_irq(&task->sighand->siglock);
+ if (__fatal_signal_pending(task))
+ wake_up_state(task, __TASK_TRACED);
+ else
+ task->state = TASK_TRACED;
+ spin_unlock_irq(&task->sighand->siglock);
+}
+
/**
* ptrace_check_attach - check whether ptracee is ready for ptrace operation
* @child: ptracee to check for
@@ -139,7 +173,7 @@ void __ptrace_unlink(struct task_struct *child)
* RETURNS:
* 0 on success, -ESRCH if %child is not ready.
*/
-int ptrace_check_attach(struct task_struct *child, bool ignore_state)
+static int ptrace_check_attach(struct task_struct *child, bool ignore_state)
{
int ret = -ESRCH;
@@ -151,24 +185,29 @@ int ptrace_check_attach(struct task_struct *child, bool ignore_state)
* be changed by us so it's not changing right after this.
*/
read_lock(&tasklist_lock);
- if ((child->ptrace & PT_PTRACED) && child->parent == current) {
+ if (child->ptrace && child->parent == current) {
+ WARN_ON(child->state == __TASK_TRACED);
/*
* child->sighand can't be NULL, release_task()
* does ptrace_unlink() before __exit_signal().
*/
- spin_lock_irq(&child->sighand->siglock);
- WARN_ON_ONCE(task_is_stopped(child));
- if (ignore_state || (task_is_traced(child) &&
- !(child->jobctl & JOBCTL_LISTENING)))
+ if (ignore_state || ptrace_freeze_traced(child))
ret = 0;
- spin_unlock_irq(&child->sighand->siglock);
}
read_unlock(&tasklist_lock);
- if (!ret && !ignore_state)
- ret = wait_task_inactive(child, TASK_TRACED) ? 0 : -ESRCH;
+ if (!ret && !ignore_state) {
+ if (!wait_task_inactive(child, __TASK_TRACED)) {
+ /*
+ * This can only happen if may_ptrace_stop() fails and
+ * ptrace_stop() changes ->state back to TASK_RUNNING,
+ * so we should not worry about leaking __TASK_TRACED.
+ */
+ WARN_ON(child->state == __TASK_TRACED);
+ ret = -ESRCH;
+ }
+ }
- /* All systems go.. */
return ret;
}
@@ -317,7 +356,7 @@ static int ptrace_attach(struct task_struct *task, long request,
*/
if (task_is_stopped(task) &&
task_set_jobctl_pending(task, JOBCTL_TRAP_STOP | JOBCTL_TRAPPING))
- signal_wake_up(task, 1);
+ signal_wake_up_state(task, __TASK_STOPPED);
spin_unlock(&task->sighand->siglock);
@@ -737,7 +776,7 @@ int ptrace_request(struct task_struct *child, long request,
* tracee into STOP.
*/
if (likely(task_set_jobctl_pending(child, JOBCTL_TRAP_STOP)))
- signal_wake_up(child, child->jobctl & JOBCTL_LISTENING);
+ ptrace_signal_wake_up(child, child->jobctl & JOBCTL_LISTENING);
unlock_task_sighand(child, &flags);
ret = 0;
@@ -763,7 +802,7 @@ int ptrace_request(struct task_struct *child, long request,
* start of this trap and now. Trigger re-trap.
*/
if (child->jobctl & JOBCTL_TRAP_NOTIFY)
- signal_wake_up(child, true);
+ ptrace_signal_wake_up(child, true);
ret = 0;
}
unlock_task_sighand(child, &flags);
@@ -900,6 +939,8 @@ SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
goto out_put_task_struct;
ret = arch_ptrace(child, request, addr, data);
+ if (ret || request != PTRACE_DETACH)
+ ptrace_unfreeze_traced(child);
out_put_task_struct:
put_task_struct(child);
@@ -1039,8 +1080,11 @@ asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
ret = ptrace_check_attach(child, request == PTRACE_KILL ||
request == PTRACE_INTERRUPT);
- if (!ret)
+ if (!ret) {
ret = compat_arch_ptrace(child, request, addr, data);
+ if (ret || request != PTRACE_DETACH)
+ ptrace_unfreeze_traced(child);
+ }
out_put_task_struct:
put_task_struct(child);
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