[merged mm-nonmm-stable] do_notify_parent-sanitize-the-valid_signal-checks.patch removed from -mm tree

[merged mm-nonmm-stable] do_notify_parent-sanitize-the-valid_signal-checks.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: do_notify_parent: sanitize the valid_signal() checks
has been removed from the -mm tree.  Its filename was
     do_notify_parent-sanitize-the-valid_signal-checks.patch

This patch was dropped because it was merged into the mm-nonmm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Oleg Nesterov <oleg@redhat.com>
Subject: do_notify_parent: sanitize the valid_signal() checks
Date: Tue, 17 Mar 2026 14:58:18 +0100

Now that kernel_clone() checks valid_signal(args->exit_signal), the "sig"
argument of do_notify_parent() must always be valid or we have a bug.

However, do_notify_parent() only checks that sig != -1 at the start, then
it does another valid_signal() check before __send_signal_locked().

This is confusing.  Change do_notify_parent() to WARN and return early if
valid_signal(sig) is false.

Link: https://lkml.kernel.org/r/abld-ilvMEZ7VgMw@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Deepanshu Kartikey <Kartikey406@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 kernel/signal.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/kernel/signal.c~do_notify_parent-sanitize-the-valid_signal-checks
+++ a/kernel/signal.c
@@ -2171,7 +2171,8 @@ bool do_notify_parent(struct task_struct
 	bool autoreap = false;
 	u64 utime, stime;
 
-	WARN_ON_ONCE(sig == -1);
+	if (WARN_ON_ONCE(!valid_signal(sig)))
+		return false;
 
 	/* do_notify_parent_cldstop should have been called instead.  */
 	WARN_ON_ONCE(task_is_stopped_or_traced(tsk));
@@ -2252,7 +2253,7 @@ bool do_notify_parent(struct task_struct
 	 * Send with __send_signal as si_pid and si_uid are in the
 	 * parent's namespaces.
 	 */
-	if (valid_signal(sig) && sig)
+	if (sig)
 		__send_signal_locked(sig, &info, tsk->parent, PIDTYPE_TGID, false);
 	__wake_up_parent(tsk, tsk->parent);
 	spin_unlock_irqrestore(&psig->siglock, flags);
_

Patches currently in -mm which might be from oleg@redhat.com are

kernel-fork-validate-exit_signal-in-kernel_clone-fix.patch