6.12-stable patches

added patches:
	posix-timers-target-group-sigqueue-to-current-task-only-if-not-exiting.patch

diff --git a/queue-6.12/posix-timers-target-group-sigqueue-to-current-task-only-if-not-exiting.patch b/queue-6.12/posix-timers-target-group-sigqueue-to-current-task-only-if-not-exiting.patch
new file mode 100644 (file)
index 0000000..dbe0db7
--- /dev/null
+++ b/queue-6.12/posix-timers-target-group-sigqueue-to-current-task-only-if-not-exiting.patch
@@ -0,0 +1,70 @@
+From 63dffecfba3eddcf67a8f76d80e0c141f93d44a5 Mon Sep 17 00:00:00 2001
+From: Frederic Weisbecker <frederic@kernel.org>
+Date: Sat, 23 Nov 2024 00:48:11 +0100
+Subject: posix-timers: Target group sigqueue to current task only if not exiting
+
+From: Frederic Weisbecker <frederic@kernel.org>
+
+commit 63dffecfba3eddcf67a8f76d80e0c141f93d44a5 upstream.
+
+A sigqueue belonging to a posix timer, which target is not a specific
+thread but a whole thread group, is preferrably targeted to the current
+task if it is part of that thread group.
+
+However nothing prevents a posix timer event from queueing such a
+sigqueue from a reaped yet running task. The interruptible code space
+between exit_notify() and the final call to schedule() is enough for
+posix_timer_fn() hrtimer to fire.
+
+If that happens while the current task is part of the thread group
+target, it is proposed to handle it but since its sighand pointer may
+have been cleared already, the sigqueue is dropped even if there are
+other tasks running within the group that could handle it.
+
+As a result posix timers with thread group wide target may miss signals
+when some of their threads are exiting.
+
+Fix this with verifying that the current task hasn't been through
+exit_notify() before proposing it as a preferred target so as to ensure
+that its sighand is still here and stable.
+
+complete_signal() might still reconsider the choice and find a better
+target within the group if current has passed retarget_shared_pending()
+already.
+
+Fixes: bcb7ee79029d ("posix-timers: Prefer delivery of signals to the current thread")
+Reported-by: Anthony Mallet <anthony.mallet@laas.fr>
+Suggested-by: Oleg Nesterov <oleg@redhat.com>
+Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
+Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
+Acked-by: Oleg Nesterov <oleg@redhat.com>
+Cc: stable@vger.kernel.org
+Link: https://lore.kernel.org/all/20241122234811.60455-1-frederic@kernel.org
+Closes: https://lore.kernel.org/all/26411.57288.238690.681680@gargle.gargle.HOWL
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ kernel/signal.c |    9 +++++----
+ 1 file changed, 5 insertions(+), 4 deletions(-)
+
+--- a/kernel/signal.c
++++ b/kernel/signal.c
+@@ -1986,14 +1986,15 @@ int send_sigqueue(struct sigqueue *q, st
+        * into t->pending).
+        *
+        * Where type is not PIDTYPE_PID, signals must be delivered to the
+-       * process. In this case, prefer to deliver to current if it is in
+-       * the same thread group as the target process, which avoids
+-       * unnecessarily waking up a potentially idle task.
++       * process. In this case, prefer to deliver to current if it is in the
++       * same thread group as the target process and its sighand is stable,
++       * which avoids unnecessarily waking up a potentially idle task.
+        */
+       t = pid_task(pid, type);
+       if (!t)
+               goto ret;
+-      if (type != PIDTYPE_PID && same_thread_group(t, current))
++      if (type != PIDTYPE_PID &&
++          same_thread_group(t, current) && !current->exit_state)
+               t = current;
+       if (!likely(lock_task_sighand(t, &flags)))
+               goto ret;

diff --git a/queue-6.12/series b/queue-6.12/series
index 55ad6900b32f7b0c2e2f5ce09955a0382f29bf6f..b34df0c7e56c30769fc09708b9353046c4f5a84b 100644 (file)
--- a/queue-6.12/series
+++ b/queue-6.12/series
@@ -143,3 +143,4 @@ drm-amd-pm-remove-arcturus-min-power-limit.patch
 drm-amd-display-fix-handling-of-plane-refcount.patch
 drm-amd-display-update-pipe-selection-policy-to-check-head-pipe.patch
 drm-amd-display-remove-pipe_dto_src_sel-programming-from-set_dtbclk_dto.patch
+posix-timers-target-group-sigqueue-to-current-task-only-if-not-exiting.patch