dm log writes: fix check of kthread_run() return value

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@mleia.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/md/dm-log-writes.c b/drivers/md/dm-log-writes.c
index 624589d..c2f2972 100644 (file)
--- 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_target *ti, unsigned int argc, char **argv)
                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);