dm rq: cope with DM device destruction while in dm_old_request_fn()

Fixes a crash in dm_table_find_target() due to a NULL struct dm_table being passed from dm_old_request_fn() that races with DM device destruction. Reported-by: [email protected] Signed-off-by: Mike Snitzer <[email protected]> Cc: [email protected]
libos-nuse · Feb 3, 2017 · 4087a1f · 4087a1f
1 parent d19a55c
commit 4087a1f
Showing 1 changed file with 4 additions and 0 deletions.
diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c
@@ -779,6 +779,10 @@ static void dm_old_request_fn(struct request_queue *q)
 		int srcu_idx;
 		struct dm_table *map = dm_get_live_table(md, &srcu_idx);
 
+		if (unlikely(!map)) {
+			dm_put_live_table(md, srcu_idx);
+			return;
+		}
 		ti = dm_table_find_target(map, pos);
 		dm_put_live_table(md, srcu_idx);
 	}