5.4.74-rt42-rc2 stable review patch. If anyone has any objections, please let me know.
------------------ From: Oleg Nesterov <[email protected]> The patch "ptrace: fix ptrace vs tasklist_lock race" changed ptrace_freeze_traced() to take task->saved_state into account, but ptrace_unfreeze_traced() has the same problem and needs a similar fix: it should check/update both ->state and ->saved_state. Reported-by: Luis Claudio R. Goncalves <[email protected]> Fixes: "ptrace: fix ptrace vs tasklist_lock race" Signed-off-by: Oleg Nesterov <[email protected]> Signed-off-by: Sebastian Andrzej Siewior <[email protected]> Cc: [email protected] Signed-off-by: Steven Rostedt (VMware) <[email protected]> --- kernel/ptrace.c | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-) diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 3075006d720e..3f7156f06b6c 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -197,8 +197,8 @@ static bool ptrace_freeze_traced(struct task_struct *task) static void ptrace_unfreeze_traced(struct task_struct *task) { - if (task->state != __TASK_TRACED) - return; + unsigned long flags; + bool frozen = true; WARN_ON(!task->ptrace || task->parent != current); @@ -207,12 +207,19 @@ static void ptrace_unfreeze_traced(struct task_struct *task) * Recheck state under the lock to close this race. */ spin_lock_irq(&task->sighand->siglock); - if (task->state == __TASK_TRACED) { - if (__fatal_signal_pending(task)) - wake_up_state(task, __TASK_TRACED); - else - task->state = TASK_TRACED; - } + + raw_spin_lock_irqsave(&task->pi_lock, flags); + if (task->state == __TASK_TRACED) + task->state = TASK_TRACED; + else if (task->saved_state == __TASK_TRACED) + task->saved_state = TASK_TRACED; + else + frozen = false; + raw_spin_unlock_irqrestore(&task->pi_lock, flags); + + if (frozen && __fatal_signal_pending(task)) + wake_up_state(task, __TASK_TRACED); + spin_unlock_irq(&task->sighand->siglock); } -- 2.28.0
