From 79afcbf09b5a197faa63f2f7021c33adca607872 Mon Sep 17 00:00:00 2001
From: John Crispin <john@phrozen.org>
Date: Mon, 30 Oct 2017 17:29:46 +0530
Subject: [PATCH] serial: do not accept sysrq characters via serial port
many embedded boards have a disconnected TTL level serial which can
generate some garbage that can lead to spurious false sysrq detects.
[john@phrozen.org: sent upstream 22.12.2016]
Signed-off-by: John Crispin <john@phrozen.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
include/linux/serial_core.h | 2 +-
lib/Kconfig.debug | 5 +++++
2 files changed, 6 insertions(+), 1 deletion(-)
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 7b16c5322..d35169123 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -455,7 +455,7 @@ extern void uart_handle_cts_change(struct uart_port *uport,
extern void uart_insert_char(struct uart_port *port, unsigned int status,
unsigned int overrun, unsigned int ch, unsigned int flag);
-#ifdef SUPPORT_SYSRQ
+#if defined(SUPPORT_SYSRQ) && defined(CONFIG_MAGIC_SYSRQ_SERIAL)
static inline int
uart_handle_sysrq_char(struct uart_port *port, unsigned int ch)
{
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 58a22ca10..08bc93a55 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -396,6 +396,11 @@ config MAGIC_SYSRQ_DEFAULT_ENABLE
This may be set to 1 or 0 to enable or disable them all, or
to a bitmask as described in Documentation/sysrq.txt.
+config MAGIC_SYSRQ_SERIAL
+ bool "Enable magic SysRq key over serial"
+ depends on MAGIC_SYSRQ
+ default y
+
config DEBUG_KERNEL
bool "Kernel debugging"
help
--
GitLab