diff options
Diffstat (limited to 'features/rt/ptrace-fix-ptrace_unfreeze_traced-race-with-rt-lock.patch')
| -rw-r--r-- | features/rt/ptrace-fix-ptrace_unfreeze_traced-race-with-rt-lock.patch | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/features/rt/ptrace-fix-ptrace_unfreeze_traced-race-with-rt-lock.patch b/features/rt/ptrace-fix-ptrace_unfreeze_traced-race-with-rt-lock.patch new file mode 100644 index 00000000..03d44b47 --- /dev/null +++ b/features/rt/ptrace-fix-ptrace_unfreeze_traced-race-with-rt-lock.patch @@ -0,0 +1,64 @@ +From 543c77838755c4c7554a11241e89298a8aae0679 Mon Sep 17 00:00:00 2001 +From: Oleg Nesterov <oleg@redhat.com> +Date: Tue, 3 Nov 2020 12:39:01 +0100 +Subject: [PATCH 129/191] ptrace: fix ptrace_unfreeze_traced() race with + rt-lock + +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 +--- + kernel/ptrace.c | 23 +++++++++++++++-------- + 1 file changed, 15 insertions(+), 8 deletions(-) + +diff --git a/kernel/ptrace.c b/kernel/ptrace.c +index 3bb0ec669997..95025b90810f 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); + } + +-- +2.19.1 + |