[PATCH] kgdbts: Passing ekgdbts to command line causes panic

[Defang Bo]

Similar to commit<1bd54d85>,kgdbts_option_setup does not check input argument
before passing it to strlen. The argument would be a NULL pointer.

Signed-off-by: Defang Bo <bodefang@xxxxxxx>
---
 drivers/misc/kgdbts.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/misc/kgdbts.c b/drivers/misc/kgdbts.c
index 945701b..99d9795 100644
--- a/drivers/misc/kgdbts.c
+++ b/drivers/misc/kgdbts.c
@@ -1057,6 +1057,11 @@ static void kgdbts_run_tests(void)
 
 static int kgdbts_option_setup(char *opt)
 {
+	if (!opt) {
+		pr_err("kgdbts: config string not provided\n");
+		return -EINVAL;
+	}
+
 	if (strlen(opt) >= MAX_CONFIG_LEN) {
 		printk(KERN_ERR "kgdbts: config string too long\n");
 		return -ENOSPC;
-- 
2.7.4