[syzbot] [input?] KASAN: slab-use-after-free Read in atkbd_set_repeat_rate

[Jeffin Philip]

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 818bebeb63dd

diff --git a/drivers/input/keyboard/atkbd.c b/drivers/input/keyboard/atkbd.c
index 5736f4bc5a50..056aa98f13e2 100644
--- a/drivers/input/keyboard/atkbd.c
+++ b/drivers/input/keyboard/atkbd.c
@@ -706,6 +706,7 @@ static inline void atkbd_enable(struct atkbd *atkbd)
 
 static inline void atkbd_disable(struct atkbd *atkbd)
 {
+	guard(mutex)(atkbd->mutex);
 	guard(serio_pause_rx)(atkbd->ps2dev.serio);
 
 	atkbd->enabled = false;