linux-kernel - [PATCH v11 21/56] Input: atmel_mxt_ts - check data->input_dev is not null in mxt_input

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Date:   Thu, 7 May 2020 22:56:21 -0700
From:   Jiada Wang <jiada_wang@...tor.com>
To:     <nick@...anahar.org>, <dmitry.torokhov@...il.com>,
        <jikos@...nel.org>, <benjamin.tissoires@...hat.com>,
        <bsz@...ihalf.com>
CC:     <linux-input@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <erosca@...adit-jv.com>, <Andrew_Gabbasov@...tor.com>,
        <jiada_wang@...tor.com>
Subject: [PATCH v11 21/56] Input: atmel_mxt_ts - check data->input_dev is not null in mxt_input_sync()

From: Janus Cheng <drxaero@...il.com>

* Symptom: if update_fw and update_cfg, kernel panic occurs.
* Reproducibility: 10%
* Root Cause:
  - If update_fw, the T6 will send a CFG_ERR message periodically.
  - After that, update_cfg process begin, the mxt_update_cfg_store() will
    invoke mxt_free_input_device() and nullify data->input_dev.
  - The CFG_ERR message will trigger mxt_interrupt(), and mxt_input_sync()
    will be invoked by mxt_process_messages_t44(). And mxt_input_sync()
    references a NULL data->input_dev and kernel panic occurs.

TrackerRMS TKT-004235

Signed-off-by: Janus Cheng <drxaero@...il.com>
Signed-off-by: Nick Dyer <nick.dyer@...ev.co.uk>
(cherry picked from ndyer/linux/for-upstream commit c909ada856861f305653b127db3ea0fa60264331)
[gdavis: Resolve forward port conflicts due to applying upstream
	 commit 96a938aa214e ("Input: atmel_mxt_ts - remove platform
	 data support").]
Signed-off-by: George G. Davis <george_davis@...tor.com>
Signed-off-by: Jiada Wang <jiada_wang@...tor.com>
---
 drivers/input/touchscreen/atmel_mxt_ts.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
index 503e70603a67..85b903b8d5c9 100644
--- a/drivers/input/touchscreen/atmel_mxt_ts.c
+++ b/drivers/input/touchscreen/atmel_mxt_ts.c
@@ -838,9 +838,11 @@ static void mxt_input_button(struct mxt_data *data, u8 *message)
 
 static void mxt_input_sync(struct mxt_data *data)
 {
-	input_mt_report_pointer_emulation(data->input_dev,
-					  data->t19_num_keys);
-	input_sync(data->input_dev);
+	if (data->input_dev) {
+		input_mt_report_pointer_emulation(data->input_dev,
+						  data->t19_num_keys);
+		input_sync(data->input_dev);
+	}
 }
 
 static void mxt_proc_t9_message(struct mxt_data *data, u8 *message)
-- 
2.17.1