From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 80CA1401A18 for ; Mon, 5 Oct 2026 10:15:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791195314; cv=none; b=Le2stcUckHBpw4S6w0f8JKkSCaFeAzja3DWm+QHj22hLIeeiLv/xXjS2mwKHQk9HGYAuAf7DrVKjvZ2S1EycAfLJMyQpyOOM/uAOF6/bIqAySdJDVXGdwvCXFeeS5qrhLKwoqKH/wYRHTGrtp7ZDZiJq4K34nP65JyouJtNQKB0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791195314; c=relaxed/simple; bh=iAspGacT+x0WwVeTIptuxh7Rz1wCeJNOCBjxZucs/iU=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=jCEdb4UWAC+JjmKwv0z74FNF+Vqdz/nTkBOaC+bRWvan6tdZ+bHR6MZKr6fW+IN3sofM7CtRERd4Ox/A5gJCBElPQBl4CbnJluMJZYPi4HxyAyGbMPKCo1oFFJx4cboDqQijP7YCeHUvSZcsjTf1hUDkJhweUM4qyCJLhZlZPyE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=yihJrBzn; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="yihJrBzn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D93511F00898; Mon, 5 Oct 2026 10:15:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1791195313; bh=5VwgeNqUYsQUzcbTV1ASx+/wippJKwuQFERag15grh0=; h=Subject:To:Cc:From:Date; b=yihJrBznNFUHxfUR0AUOVyNwBYtB9OH9PGpcU72NhUpxNbGBVc+R8k0wTTWUj2lBP qHwPik+ZaLRmVyCz7RsDs4gcnIHhWj4Mc1WNgE9agKtoA5afg4564eV5cf6aG19vdF J8XFVPl+GoXeXx5HqPhWLBJOyaTn9sSGZvU146tU= Subject: FAILED: patch "[PATCH] serial: core: fix NULL pointer dereference in" failed to apply to 6.12-stable tree To: linuxoid@gmail.com,gregkh@linuxfoundation.org,tony.lindgren@linux.intel.com Cc: From: Date: Mon, 05 Oct 2026 12:15:01 +0200 Message-ID: <2026100501-doily-overblown-7da9@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.12-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y git checkout FETCH_HEAD git cherry-pick -x 499485a67fbacf4d9afbdb43522388c64f853428 # git commit -s git send-email --to '' --in-reply-to '2026100501-doily-overblown-7da9@gregkh' --subject-prefix 'PATCH 6.12.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 499485a67fbacf4d9afbdb43522388c64f853428 Mon Sep 17 00:00:00 2001 From: Ruslan Valiyev Date: Wed, 26 Aug 2026 10:46:54 +0200 Subject: [PATCH] serial: core: fix NULL pointer dereference in serial_core_unregister_port() port->port_dev is NULL when no port device is installed: it is cleared on teardown, and never set if registration failed before serial_core_port_device_add(). serial_core_unregister_port() passes it straight to serial_core_get_ctrl_dev(), which dereferences it: KASAN: null-ptr-deref in range [0x0000000000000040-0x0000000000000047] RIP: serial_core_unregister_port Call Trace: serial8250_unregister_port serial8250_remove unbind_store Return early when there is no port device, and read port->port_dev under port_mutex. Also clear port->port_dev on the serial_core_register_port() error path, where the port device has already been removed. Fixes: 84a9582fd203 ("serial: core: Start managing serial controllers to enable runtime PM") Reported-by: syzbot+9f57c1b2792029198fcf@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=9f57c1b2792029198fcf Cc: stable@kernel.org Assisted-by: Claude:claude-opus-5 Assisted-by: Codex:gpt-5.6-sol Signed-off-by: Ruslan Valiyev Link: https://syzkaller.appspot.com/bug?extid=9f57c1b2792029198fcf Link: https://lore.kernel.org/all/20260826073237.1377668-1-linuxoid@gmail.com/ Reviewed-by: Tony Lindgren Link: https://patch.msgid.link/20260826084654.1392851-1-linuxoid@gmail.com Signed-off-by: Greg Kroah-Hartman diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 33c8f3b6ac81..6332ed545c89 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -3381,6 +3381,7 @@ int serial_core_register_port(struct uart_driver *drv, struct uart_port *port) err_unregister_port_dev: serial_base_port_device_remove(port->port_dev); + port->port_dev = NULL; err_unregister_ctrl_dev: serial_base_ctrl_device_remove(new_ctrl_dev); @@ -3395,12 +3396,24 @@ int serial_core_register_port(struct uart_driver *drv, struct uart_port *port) void serial_core_unregister_port(struct uart_driver *drv, struct uart_port *port) { struct device *phys_dev = port->dev; - struct serial_port_device *port_dev = port->port_dev; - struct serial_ctrl_device *ctrl_dev = serial_core_get_ctrl_dev(port_dev); + struct serial_port_device *port_dev; + struct serial_ctrl_device *ctrl_dev; int ctrl_id = port->ctrl_id; guard(mutex)(&port_mutex); + /* + * A NULL port device means there is no registered port device to + * remove: serial_core_remove_one_port() clears port_dev on + * teardown, and it is never set if registration failed before + * serial_core_port_device_add(). + */ + port_dev = port->port_dev; + if (!port_dev) + return; + + ctrl_dev = serial_core_get_ctrl_dev(port_dev); + port->flags |= UPF_DEAD; serial_core_remove_one_port(drv, port);