[Devel] [PATCH vz10 v2 2/2] dm-ploop: fix NULL deref in ploop_destroy() when ploop_ctr() failed early

[Konstantin Khorenko <khorenko@virtuozzo.com>]

ploop_ctr() can fail early on setting up the ploop->kt_allocator,
so ploop_destroy() must check it for NULL before dereferencing.

Fixes: 9429d1119a69 ("dm-ploop: make filespace preallocations async")
Feature: dm-ploop: ploop target driver
https://virtuozzo.atlassian.net/browse/VSTOR-137234
Signed-off-by: Konstantin Khorenko <khorenko@virtuozzo.com>
Reviewed-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
---
 drivers/md/dm-ploop-target.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/md/dm-ploop-target.c b/drivers/md/dm-ploop-target.c
index 7dab95402def7..3b589579741c6 100644
--- a/drivers/md/dm-ploop-target.c
+++ b/drivers/md/dm-ploop-target.c
@@ -188,7 +188,9 @@ static void ploop_destroy(struct ploop *ploop)
 
 		/* waits for the thread to stop */
 		kthread_stop(ploop->kt_worker->task);
-		kthread_stop(ploop->kt_allocator->task);
+		/* kt_allocator may be NULL if ploop_ctr() failed early */
+		if (ploop->kt_allocator)
+			kthread_stop(ploop->kt_allocator->task);
 
 		WARN_ON(!llist_empty(&ploop->pios[PLOOP_LIST_PREPARE]));
 		WARN_ON(!llist_empty(&ploop->llresubmit_pios));
-- 
2.43.0