From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D78513370FF; Fri, 17 Oct 2025 15:04:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760713451; cv=none; b=KPTvMhl18kx/NpsuHYVLqdGsRqiwj2rqvLD1oNCmRYx2HytbxsBCQ2gmW4Wq9hy+9+XlChRyYNgBGjq9nB/3ILgGoy4yLHrRsGV0SxrQJ3MSkVlBa1CORV7q7Ek4Hi6iJMjjO6XjJ+DwjahQUXDPRch4329xoV2oEWXEozuOT5w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760713451; c=relaxed/simple; bh=rR8iq7dNZg9CXF77RgNAnVyLp2gHny5KfFL8QaHYQbE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=ryeD0OiuJw0dFCo3q0FPneC9SrWaEUxgx1QYsCJYS/P5HtkubaJ5+F4iW34rCgd4BJJtIsd5sB0uHumjPxZr/xATwwvfGfEKt6ZtmgnQeZnJK+00FHkYnfm7k9SmpmzLZeTMhqQJ94kgm5N3mt93R60EfLKhp6S9t2FxAuvDkr4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=A47cr73h; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="A47cr73h" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 59DF0C4CEE7; Fri, 17 Oct 2025 15:04:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1760713451; bh=rR8iq7dNZg9CXF77RgNAnVyLp2gHny5KfFL8QaHYQbE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=A47cr73hthu1Yg6E+rZipHpH0ZvP/qlvWbery73p5Ai13am4iVhflhITjjl7rD5te Qi/XuE18mRePWklrWOlKAD92kF5sMW22NjJJiedyXiF4Ia59h9o6DF68OUBiXCBmtZ CfE4qnvGkUQlZGsLcw1cieg4DFkJ1fwa3bt1qXTo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Oleg Nesterov , Christian Brauner , Sasha Levin , =?UTF-8?q?=E9=AB=98=E7=BF=94?= Subject: [PATCH 6.1 163/168] pid: make __task_pid_nr_ns(ns => NULL) safe for zombie callers Date: Fri, 17 Oct 2025 16:54:02 +0200 Message-ID: <20251017145135.053471068@linuxfoundation.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251017145129.000176255@linuxfoundation.org> References: <20251017145129.000176255@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Oleg Nesterov [ Upstream commit abdfd4948e45c51b19162cf8b3f5003f8f53c9b9 ] task_pid_vnr(another_task) will crash if the caller was already reaped. The pid_alive(current) check can't really help, the parent/debugger can call release_task() right after this check. This also means that even task_ppid_nr_ns(current, NULL) is not safe, pid_alive() only ensures that it is safe to dereference ->real_parent. Change __task_pid_nr_ns() to ensure ns != NULL. Originally-by: 高翔 Link: https://lore.kernel.org/all/20250802022123.3536934-1-gxxa03070307@gmail.com/ Signed-off-by: Oleg Nesterov Link: https://lore.kernel.org/20250810173604.GA19991@redhat.com Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin --- kernel/pid.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/pid.c b/kernel/pid.c index e1d0c9d952278..62a8349267de1 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -497,7 +497,8 @@ pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type, rcu_read_lock(); if (!ns) ns = task_active_pid_ns(current); - nr = pid_nr_ns(rcu_dereference(*task_pid_ptr(task, type)), ns); + if (ns) + nr = pid_nr_ns(rcu_dereference(*task_pid_ptr(task, type)), ns); rcu_read_unlock(); return nr; -- 2.51.0