linux-kernel - [PATCH] HID: wacom: check for wacom->shared before following the pointer

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Message-Id: <1425594995-22958-1-git-send-email-benjamin.tissoires@redhat.com>
Date:	Thu,  5 Mar 2015 17:36:35 -0500
From:	Benjamin Tissoires <benjamin.tissoires@...hat.com>
To:	Jiri Kosina <jkosina@...e.cz>, Ping Cheng <pinglinux@...il.com>,
	Jason Gerecke <killertofu@...il.com>
Cc:	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] HID: wacom: check for wacom->shared before following the pointer

486b908 (HID: wacom: do not send pen events before touch is up/forced out)
introduces a kernel oops when plugging a tablet without touch.

wacom->shared is null for these devices so this leads to a null pointer
exception.

Change the condition to make it clear that what we need is wacom->shared
not NULL.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...hat.com>
---

Hi Jiri,

this one should be pulled in 4.0. Or we will have surprised users :)

Cheers,
Benjamin

 drivers/hid/wacom_wac.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c
index ff9a7ab..9739a4c 100644
--- a/drivers/hid/wacom_wac.c
+++ b/drivers/hid/wacom_wac.c
@@ -564,11 +564,12 @@ static int wacom_intuos_inout(struct wacom_wac *wacom)
 	   (features->type == CINTIQ && !(data[1] & 0x40)))
 		return 1;
 
-	if (features->quirks & WACOM_QUIRK_MULTI_INPUT)
+	if (wacom->shared) {
 		wacom->shared->stylus_in_proximity = true;
 
-	if (wacom->shared->touch_down)
-		return 1;
+		if (wacom->shared->touch_down)
+			return 1;
+	}
 
 	/* in Range while exiting */
 	if (((data[1] & 0xfe) == 0x20) && wacom->reporting_data) {
-- 
2.1.0

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