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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Hans Verkuil <hverkuil-cisco@xs4all.nl>,
        syzbot+53d5b2df0d9744411e2e@syzkaller.appspotmail.com,
        Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Subject: [PATCH 4.9 32/51] media: vivid: fix error handling of kthread_run
Date:   Mon, 21 Jan 2019 14:44:28 +0100
Message-Id: <20190121122456.707494327@linuxfoundation.org>
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4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Hans Verkuil <hverkuil-cisco@xs4all.nl>

commit 701f49bc028edb19ffccd101997dd84f0d71e279 upstream.

kthread_run returns an error pointer, but elsewhere in the code
dev->kthread_vid_cap/out is checked against NULL.

If kthread_run returns an error, then set the pointer to NULL.

I chose this method over changing all kthread_vid_cap/out tests
elsewhere since this is more robust.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reported-by: syzbot+53d5b2df0d9744411e2e@syzkaller.appspotmail.com
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/media/platform/vivid/vivid-kthread-cap.c |    5 ++++-
 drivers/media/platform/vivid/vivid-kthread-out.c |    5 ++++-
 2 files changed, 8 insertions(+), 2 deletions(-)

--- a/drivers/media/platform/vivid/vivid-kthread-cap.c
+++ b/drivers/media/platform/vivid/vivid-kthread-cap.c
@@ -877,8 +877,11 @@ int vivid_start_generating_vid_cap(struc
 			"%s-vid-cap", dev->v4l2_dev.name);
 
 	if (IS_ERR(dev->kthread_vid_cap)) {
+		int err = PTR_ERR(dev->kthread_vid_cap);
+
+		dev->kthread_vid_cap = NULL;
 		v4l2_err(&dev->v4l2_dev, "kernel_thread() failed\n");
-		return PTR_ERR(dev->kthread_vid_cap);
+		return err;
 	}
 	*pstreaming = true;
 	vivid_grab_controls(dev, true);
--- a/drivers/media/platform/vivid/vivid-kthread-out.c
+++ b/drivers/media/platform/vivid/vivid-kthread-out.c
@@ -248,8 +248,11 @@ int vivid_start_generating_vid_out(struc
 			"%s-vid-out", dev->v4l2_dev.name);
 
 	if (IS_ERR(dev->kthread_vid_out)) {
+		int err = PTR_ERR(dev->kthread_vid_out);
+
+		dev->kthread_vid_out = NULL;
 		v4l2_err(&dev->v4l2_dev, "kernel_thread() failed\n");
-		return PTR_ERR(dev->kthread_vid_out);
+		return err;
 	}
 	*pstreaming = true;
 	vivid_grab_controls(dev, true);