linux-kernel - stack leak via uart_get

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Message-ID: <967b9ef1-fb36-48bf-9e6a-1b99af24c052@p183>
Date:   Thu, 5 Oct 2023 19:34:21 +0300
From:   Alexey Dobriyan <adobriyan@...il.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>
Cc:     linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: stack leak via uart_get_info() ?

If this check ever triggers

	static int uart_get_info(struct tty_port *port, struct serial_struct *retinfo)
	{

		uport = uart_port_check(state);
	        if (!uport)
	                goto out;

then all those sysfs users will print stack contents to userspace.

Can it trigger while sysfs read is executing?


Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
---

--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -775,6 +775,8 @@ static int uart_get_info(struct tty_port *port, struct serial_struct *retinfo)
 	struct uart_port *uport;
 	int ret = -ENODEV;
 
+	*retinfo = (struct serial_struct){};
+
 	/*
 	 * Ensure the state we copy is consistent and no hardware changes
 	 * occur as we go