[PATCH] Input: psmouse: add NULL check to psmouse_from_serio()

[Takashi Iwai]

The serio drvdata can be still NULL while the PS/2 interrupt is
processed.  This leaded to crash with a NULL dereference Oops, as
psmouse_from_serio() blindly assumes the non-NULL ps2dev object.

Add a NULL check and return NULL from psmouse_from_serio().  The
returned NULL is handled properly in the caller side, skipping the
rest gracefully.

The log in the bugzilla entry showed that the probe of synaptics
driver succeeded after that point.  So this is a stop-gap solution.

Link: https://bugzilla.suse.com/show_bug.cgi?id=1219522
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
---

 drivers/input/mouse/psmouse-base.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/input/mouse/psmouse-base.c b/drivers/input/mouse/psmouse-base.c
index a0aac76b1e41..fdeee7578d18 100644
--- a/drivers/input/mouse/psmouse-base.c
+++ b/drivers/input/mouse/psmouse-base.c
@@ -120,6 +120,8 @@ struct psmouse *psmouse_from_serio(struct serio *serio)
 {
 	struct ps2dev *ps2dev = serio_get_drvdata(serio);
 
+	if (!ps2dev)
+		return NULL;
 	return container_of(ps2dev, struct psmouse, ps2dev);
 }
 
-- 
2.43.0