diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2020-11-03 12:39:01 +0100 |
|---|---|---|
| committer | Mark Gross <markgross@kernel.org> | 2022-03-02 16:43:06 -0800 |
| commit | 927cf4cc62bf7c41e5dbe74a111699819b79bcdf (patch) | |
| tree | 094980a6b1365e3a2c334b1150d851db331f0843 | |
| parent | 209424478b42f12331dc4513d421909690d1b56b (diff) | |
| download | linux-rt-927cf4cc62bf7c41e5dbe74a111699819b79bcdf.tar.gz | |
ptrace: fix ptrace_unfreeze_traced() race with rt-lock
[ Upstream commit 0fdc91971b34cf6857b4cfd8c322ae936cfc189b ]
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 <lgoncalv@redhat.com>
Fixes: "ptrace: fix ptrace vs tasklist_lock race"
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: stable-rt@vger.kernel.org
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
| -rw-r--r-- | kernel/ptrace.c | 23 |
1 files changed, 15 insertions, 8 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c index cd869b487adc..c738827f29f7 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -203,8 +203,8 @@ 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); @@ -213,12 +213,19 @@ 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); } |