linux-kernel - [PATCH 5.16 0688/1017] clk: Fix clk_hw_get

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Date:   Tue,  5 Apr 2022 09:26:41 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Maxime Ripard <maxime@...no.tech>,
        Stephen Boyd <sboyd@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.16 0688/1017] clk: Fix clk_hw_get_clk() when dev is NULL

From: Maxime Ripard <maxime@...no.tech>

[ Upstream commit 0c1b56df451716ba207bbf59f303473643eee4fd ]

Any registered clk_core structure can have a NULL pointer in its dev
field. While never actually documented, this is evidenced by the wide
usage of clk_register and clk_hw_register with a NULL device pointer,
and the fact that the core of_clk_hw_register() function also passes a
NULL device pointer.

A call to clk_hw_get_clk() on a clk_hw struct whose clk_core is in that
case will result in a NULL pointer derefence when it calls dev_name() on
that NULL device pointer.

Add a test for this case and use NULL as the dev_id if the device
pointer is NULL.

Fixes: 30d6f8c15d2c ("clk: add api to get clk consumer from clk_hw")
Signed-off-by: Maxime Ripard <maxime@...no.tech>
Link: https://lore.kernel.org/r/20220225143534.405820-2-maxime@cerno.tech
Signed-off-by: Stephen Boyd <sboyd@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/clk/clk.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 21b17d6ced6d..e55ddc12ed53 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -3733,8 +3733,9 @@ struct clk *clk_hw_create_clk(struct device *dev, struct clk_hw *hw,
 struct clk *clk_hw_get_clk(struct clk_hw *hw, const char *con_id)
 {
 	struct device *dev = hw->core->dev;
+	const char *name = dev ? dev_name(dev) : NULL;
 
-	return clk_hw_create_clk(dev, hw, dev_name(dev), con_id);
+	return clk_hw_create_clk(dev, hw, name, con_id);
 }
 EXPORT_SYMBOL(clk_hw_get_clk);
 
-- 
2.34.1