[PATCH 5.16 0705/1017] kgdboc: fix return value of __setup handler

From: Greg Kroah-Hartman
Date: Tue Apr 05 2022 - 09:14:50 EST

From: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>

[ Upstream commit ab818c7aa7544bf8d2dd4bdf68878b17a02eb332 ]

__setup() handlers should return 1 to obsolete_checksetup() in
init/main.c to indicate that the boot option has been handled.
A return of 0 causes the boot option/value to be listed as an Unknown
kernel parameter and added to init's (limited) environment strings.
So return 1 from kgdboc_option_setup().

Unknown kernel command line parameters "BOOT_IMAGE=/boot/bzImage-517rc7
kgdboc=kbd kgdbts=", will be passed to user space.

Run /sbin/init as init process
with arguments:
with environment:

Link: lore.kernel.org/r/64644a2f-4a20-bab3-1e15-3b2cdd0defe3@xxxxxxxxxxxx
Fixes: 1bd54d851f50 ("kgdboc: Passing ekgdboc to command line causes panic")
Fixes: f2d937f3bf00 ("consoles: polling support, kgdboc")
Cc: He Zhe <zhe.he@xxxxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Jiri Slaby <jirislaby@xxxxxxxxxx>
Cc: kgdb-bugreport@xxxxxxxxxxxxxxxxxxxxx
Cc: Jason Wessel <jason.wessel@xxxxxxxxxxxxx>
Cc: Daniel Thompson <daniel.thompson@xxxxxxxxxx>
Cc: Douglas Anderson <dianders@xxxxxxxxxxxx>
Cc: linux-serial@xxxxxxxxxxxxxxx
Reported-by: Igor Zhbanov <i.zhbanov@xxxxxxxxxxxx>
Reviewed-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220309033018.17936-1-rdunlap@xxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
drivers/tty/serial/kgdboc.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/kgdboc.c b/drivers/tty/serial/kgdboc.c
index 49d0c7f2b29b..79b7db8580e0 100644
--- a/drivers/tty/serial/kgdboc.c
+++ b/drivers/tty/serial/kgdboc.c
@@ -403,16 +403,16 @@ static int kgdboc_option_setup(char *opt)
if (!opt) {
pr_err("config string not provided\n");
- return -EINVAL;
+ return 1;

if (strlen(opt) >= MAX_CONFIG_LEN) {
pr_err("config string too long\n");
- return -ENOSPC;
+ return 1;
strcpy(config, opt);

- return 0;
+ return 1;

__setup("kgdboc=", kgdboc_option_setup);