1 files changed, 3 insertions, 0 deletions
diff --git a/block.c b/block.c
index 79d9ad0ad6..74ac7dcf74 100644
--- a/block.c
+++ b/block.c
@@ -3122,6 +3122,9 @@ int bdrv_truncate(BdrvChild *child, int64_t offset)
     BlockDriverState *bs = child->bs;
     BlockDriver *drv = bs->drv;
     int ret;
+
+    assert(child->perm & BLK_PERM_RESIZE);
+
     if (!drv)
         return -ENOMEDIUM;
     if (!drv->bdrv_truncate)