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Subject: [PATCH v2 1/3] HID: hid-bigbenff: fix general protection fault caused
 by double kfree
From:   Hanno Zulla <kontakt@hanno.de>
To:     Benjamin Tissoires <benjamin.tissoires@redhat.com>
Cc:     Jiri Kosina <jikos@kernel.org>,
        "open list:HID CORE LAYER" <linux-input@vger.kernel.org>,
        lkml <linux-kernel@vger.kernel.org>
References: <ae5eee33-9dfc-0609-1bf8-33fd773b9bd5@hanno.de>
 <CAO-hwJJ1sc_RAh4ytWSOmRqfVESi2dvB_Ao_Vn+6XXixxVyxrA@mail.gmail.com>
 <74d73ebc-0cff-768d-00b7-57bb9b44124f@hanno.de>
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Date:   Tue, 18 Feb 2020 12:37:47 +0100
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HID: hid-bigbenff: fix general protection fault caused by double kfree

The struct *bigben was allocated via devm_kzalloc() and then used as a
parameter in input_ff_create_memless(). This caused a double kfree
during removal of the device, since both the managed resource API and
ml_ff_destroy() in drivers/input/ff-memless.c would call kfree() on it.

Signed-off-by: Hanno Zulla <kontakt@hanno.de>
---
 drivers/hid/hid-bigbenff.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/hid/hid-bigbenff.c b/drivers/hid/hid-bigbenff.c
index 3f6abd190df4..f7e85bacb688 100644
--- a/drivers/hid/hid-bigbenff.c
+++ b/drivers/hid/hid-bigbenff.c
@@ -220,10 +220,16 @@ static void bigben_worker(struct work_struct *work)
 static int hid_bigben_play_effect(struct input_dev *dev, void *data,
 			 struct ff_effect *effect)
 {
-	struct bigben_device *bigben = data;
+	struct hid_device *hid = input_get_drvdata(dev);
+	struct bigben_device *bigben = hid_get_drvdata(hid);
 	u8 right_motor_on;
 	u8 left_motor_force;
 
+	if (!bigben) {
+		hid_err(hid, "no device data\n");
+		return 0;
+	}
+
 	if (effect->type != FF_RUMBLE)
 		return 0;
 
@@ -341,7 +347,7 @@ static int bigben_probe(struct hid_device *hid,
 
 	INIT_WORK(&bigben->worker, bigben_worker);
 
-	error = input_ff_create_memless(hidinput->input, bigben,
+	error = input_ff_create_memless(hidinput->input, NULL,
 		hid_bigben_play_effect);
 	if (error)
 		return error;
-- 
2.20.1