Closed Miouyouyou closed 5 years ago
Miouyouyou
commented
5 years ago Barely nothing changed beside this :
https://elixir.bootlin.com/linux/v5.0-rc2/source/drivers/tty/serial/8250/8250_core.c#L1076 ( Previous code : https://elixir.bootlin.com/linux/v4.20.2/source/drivers/tty/serial/8250/8250_core.c#L1059 )
So this might be the issue. I'll check tomorrow.
Miouyouyou
commented
5 years ago This resolves the issue :
From 7e43ae8446b420907f00b43308ad0b99b6fe4e51 Mon Sep 17 00:00:00 2001
From: "Miouyouyou (Myy)" <myy@miouyouyou.fr>
Date: Wed, 16 Jan 2019 23:58:52 +0100
Subject: [PATCH] drivers: tty: serial: Bail out if no UART is detected
Before the 5.0, serial8250_register_8250_port consisted of one BIG
if(uart && uart->port.type != PORT_8250_CIR) block, which prevented
NULL dereference if uart, a pointer to an "uart_8250_port" detected
through "serial8250_find_match_or_unused", were to be NULL.
However, a recent patch added a few bits of code just after that,
and that code manipulates the "uart" pointer without checking if
it's NULL or not.
This patch changes the mechanism and bail out early if no UART
structure pointer is provided serial8250_find_match_or_unused.
A goto is used instead of returning directly, since we're inside
a mutex and must release it correctly.
Signed-off-by: Miouyouyou (Myy) <myy@miouyouyou.fr>
---
drivers/tty/serial/8250/8250_core.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 189ab1212..11120c2d9 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -981,7 +981,12 @@ int serial8250_register_8250_port(struct uart_8250_port *up)
mutex_lock(&serial_mutex);
uart = serial8250_find_match_or_unused(&up->port);
- if (uart && uart->port.type != PORT_8250_CIR) {
+ if (!uart) {
+ printk(KERN_INFO "One UART port failed to register correctly\n");
+ goto no_uart;
+ }
+
+ if (uart->port.type != PORT_8250_CIR) {
if (uart->port.dev)
uart_remove_one_port(&serial8250_reg, &uart->port);
@@ -1081,6 +1086,7 @@ int serial8250_register_8250_port(struct uart_8250_port *up)
uart->overrun_backoff_time_ms = 0;
}
+no_uart:
mutex_unlock(&serial_mutex);
return ret;
--
2.16.4
The following issue arises when trying to boot a 5.0-rc2 with no patches on a Tinkerboard :
Given than I tried with and without any patches, I can conclude that it's the current state of the 5.0 kernel.
I'll try to investigate this.