linux-kernel - [PATCH 4.4 061/118] dm log writes: fix check of kthread

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Date:   Thu, 22 Sep 2016 19:29:21 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Vladimir Zapolskiy <vz@...ia.com>,
        Mike Snitzer <snitzer@...hat.com>
Subject: [PATCH 4.4 061/118] dm log writes: fix check of kthread_run() return value

4.4-stable review patch.  If anyone has any objections, please let me know.

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

From: Vladimir Zapolskiy <vz@...ia.com>

commit 91e630d9ae6de6f740ef7c8176736eb55366833e upstream.

The kthread_run() function returns either a valid task_struct or
ERR_PTR() value, check for NULL is invalid.  This change fixes potential
for oops, e.g. in OOM situation.

Signed-off-by: Vladimir Zapolskiy <vz@...ia.com>
Signed-off-by: Mike Snitzer <snitzer@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/md/dm-log-writes.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/md/dm-log-writes.c
+++ b/drivers/md/dm-log-writes.c
@@ -456,9 +456,9 @@ static int log_writes_ctr(struct dm_targ
 		goto bad;
 	}
 
-	ret = -EINVAL;
 	lc->log_kthread = kthread_run(log_writes_kthread, lc, "log-write");
-	if (!lc->log_kthread) {
+	if (IS_ERR(lc->log_kthread)) {
+		ret = PTR_ERR(lc->log_kthread);
 		ti->error = "Couldn't alloc kthread";
 		dm_put_device(ti, lc->dev);
 		dm_put_device(ti, lc->logdev);