[PATCH] clk: composite: fix NULL dereference when the parent clock is not set

[Haotian Zhang <vulab@iscas.ac.cn>]

clk_composite_determine_rate() reads the parent clock with
clk_hw_get_parent() and hands it to
clk_composite_determine_rate_for_parent() without checking it.
clk_hw_get_parent() returns NULL when the clock has no parent yet, for
example while the parent is still an orphan, and the helper dereferences
that NULL pointer in clk_hw_get_rate(), which reads parent_hw->core and
oopses the kernel.

Return -EINVAL when the parent clock is NULL.

Fixes: 2f508a955a67 ("clk: Convert basic types to clk_hw based provider APIs")
Assisted-by: DeepSeek-V4.1-Flash
Signed-off-by: Haotian Zhang <vulab@iscas.ac.cn>
---
 drivers/clk/clk-composite.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/clk/clk-composite.c b/drivers/clk/clk-composite.c
index 11842bce5918..40d64ef2d325 100644
--- a/drivers/clk/clk-composite.c
+++ b/drivers/clk/clk-composite.c
@@ -75,6 +75,8 @@ static int clk_composite_determine_rate(struct clk_hw *hw,
 			struct clk_rate_request tmp_req;
 
 			parent = clk_hw_get_parent(mux_hw);
+			if (!parent)
+				return -EINVAL;
 
 			clk_hw_forward_rate_request(hw, req, parent, &tmp_req, req->rate);
 			ret = clk_composite_determine_rate_for_parent(rate_hw,
-- 
2.25.1