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-rw-r--r--debian/patches-rt/0224-ptrace-fix-ptrace_unfreeze_traced-race-with-rt-lock.patch65
1 files changed, 65 insertions, 0 deletions
diff --git a/debian/patches-rt/0224-ptrace-fix-ptrace_unfreeze_traced-race-with-rt-lock.patch b/debian/patches-rt/0224-ptrace-fix-ptrace_unfreeze_traced-race-with-rt-lock.patch
new file mode 100644
index 000000000..4e61137e3
--- /dev/null
+++ b/debian/patches-rt/0224-ptrace-fix-ptrace_unfreeze_traced-race-with-rt-lock.patch
@@ -0,0 +1,65 @@
+From 10d5d8e25cce1695bb99f7149038d97b9a160201 Mon Sep 17 00:00:00 2001
+From: Oleg Nesterov <oleg@redhat.com>
+Date: Tue, 3 Nov 2020 12:39:01 +0100
+Subject: [PATCH 224/323] ptrace: fix ptrace_unfreeze_traced() race with
+ rt-lock
+Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.204-rt100.tar.xz
+
+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 71acb6341e63..fb5d1a19507d 100644
+--- a/kernel/ptrace.c
++++ b/kernel/ptrace.c
+@@ -213,8 +213,8 @@ 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);
+
+@@ -223,12 +223,19 @@ 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);
+ }
+
+--
+2.43.0
+