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-rw-r--r--block.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/block.c b/block.c
index 45f653a88b..580cb77a70 100644
--- a/block.c
+++ b/block.c
@@ -84,6 +84,9 @@ static BlockDriverState *bdrv_open_inherit(const char *filename,
BdrvChildRole child_role,
Error **errp);
+static bool bdrv_recurse_has_child(BlockDriverState *bs,
+ BlockDriverState *child);
+
static void bdrv_replace_child_noperm(BdrvChild *child,
BlockDriverState *new_bs);
static void bdrv_remove_file_or_backing_child(BlockDriverState *bs,
@@ -2673,6 +2676,7 @@ static void bdrv_replace_child_noperm(BdrvChild *child,
int drain_saldo;
assert(!child->frozen);
+ assert(old_bs != new_bs);
if (old_bs && new_bs) {
assert(bdrv_get_aio_context(old_bs) == bdrv_get_aio_context(new_bs));
@@ -2892,6 +2896,12 @@ static int bdrv_attach_child_noperm(BlockDriverState *parent_bs,
assert(parent_bs->drv);
+ if (bdrv_recurse_has_child(child_bs, parent_bs)) {
+ error_setg(errp, "Making '%s' a %s child of '%s' would create a cycle",
+ child_bs->node_name, child_name, parent_bs->node_name);
+ return -EINVAL;
+ }
+
bdrv_get_cumulative_perm(parent_bs, &perm, &shared_perm);
bdrv_child_perm(parent_bs, child_bs, NULL, child_role, NULL,
perm, shared_perm, &perm, &shared_perm);