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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>
CC:     Pan Bian <bianpan2016@163.com>,
        Hans Verkuil <hans.verkuil@cisco.com>,
        Mauro Carvalho Chehab <mchehab@s-opensource.com>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL for 4.4 129/167] [media] cx25840: fix unchecked return
 values
Thread-Topic: [PATCH AUTOSEL for 4.4 129/167] [media] cx25840: fix unchecked
 return values
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Date:   Mon, 19 Mar 2018 16:08:04 +0000
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From: Pan Bian <bianpan2016@163.com>

[ Upstream commit 35378ce143071c2a6bad4b59a000e9b9f8f6ea67 ]

In functions cx25840_initialize(), cx231xx_initialize(), and
cx23885_initialize(), the return value of create_singlethread_workqueue()
is used without validation. This may result in NULL dereference and cause
kernel crash. This patch fixes it.

Signed-off-by: Pan Bian <bianpan2016@163.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 drivers/media/i2c/cx25840/cx25840-core.c | 36 +++++++++++++++++++---------=
----
 1 file changed, 21 insertions(+), 15 deletions(-)

diff --git a/drivers/media/i2c/cx25840/cx25840-core.c b/drivers/media/i2c/c=
x25840/cx25840-core.c
index fe6eb78b6914..a47ab1947cc4 100644
--- a/drivers/media/i2c/cx25840/cx25840-core.c
+++ b/drivers/media/i2c/cx25840/cx25840-core.c
@@ -420,11 +420,13 @@ static void cx25840_initialize(struct i2c_client *cli=
ent)
 	INIT_WORK(&state->fw_work, cx25840_work_handler);
 	init_waitqueue_head(&state->fw_wait);
 	q =3D create_singlethread_workqueue("cx25840_fw");
-	prepare_to_wait(&state->fw_wait, &wait, TASK_UNINTERRUPTIBLE);
-	queue_work(q, &state->fw_work);
-	schedule();
-	finish_wait(&state->fw_wait, &wait);
-	destroy_workqueue(q);
+	if (q) {
+		prepare_to_wait(&state->fw_wait, &wait, TASK_UNINTERRUPTIBLE);
+		queue_work(q, &state->fw_work);
+		schedule();
+		finish_wait(&state->fw_wait, &wait);
+		destroy_workqueue(q);
+	}
=20
 	/* 6. */
 	cx25840_write(client, 0x115, 0x8c);
@@ -631,11 +633,13 @@ static void cx23885_initialize(struct i2c_client *cli=
ent)
 	INIT_WORK(&state->fw_work, cx25840_work_handler);
 	init_waitqueue_head(&state->fw_wait);
 	q =3D create_singlethread_workqueue("cx25840_fw");
-	prepare_to_wait(&state->fw_wait, &wait, TASK_UNINTERRUPTIBLE);
-	queue_work(q, &state->fw_work);
-	schedule();
-	finish_wait(&state->fw_wait, &wait);
-	destroy_workqueue(q);
+	if (q) {
+		prepare_to_wait(&state->fw_wait, &wait, TASK_UNINTERRUPTIBLE);
+		queue_work(q, &state->fw_work);
+		schedule();
+		finish_wait(&state->fw_wait, &wait);
+		destroy_workqueue(q);
+	}
=20
 	/* Call the cx23888 specific std setup func, we no longer rely on
 	 * the generic cx24840 func.
@@ -746,11 +750,13 @@ static void cx231xx_initialize(struct i2c_client *cli=
ent)
 	INIT_WORK(&state->fw_work, cx25840_work_handler);
 	init_waitqueue_head(&state->fw_wait);
 	q =3D create_singlethread_workqueue("cx25840_fw");
-	prepare_to_wait(&state->fw_wait, &wait, TASK_UNINTERRUPTIBLE);
-	queue_work(q, &state->fw_work);
-	schedule();
-	finish_wait(&state->fw_wait, &wait);
-	destroy_workqueue(q);
+	if (q) {
+		prepare_to_wait(&state->fw_wait, &wait, TASK_UNINTERRUPTIBLE);
+		queue_work(q, &state->fw_work);
+		schedule();
+		finish_wait(&state->fw_wait, &wait);
+		destroy_workqueue(q);
+	}
=20
 	cx25840_std_setup(client);
=20
--=20
2.14.1