[PATCH AUTOSEL for 4.15 57/78] clk: check ops pointer on clock register

[Sasha Levin]

From: Jerome Brunet <jbrunet@xxxxxxxxxxxx>

[ Upstream commit 29fd2a34ef8d863e48183bd473ba57c8d7839e25 ]

Nothing really prevents a provider from (trying to) register a clock
without providing the clock ops structure.

We do check the individual fields before using them, but not the
structure pointer itself. This may have the usual nasty consequences when
the pointer is dereferenced, most likely when checking one the field
during the initialization.

This is fixed by returning an error on clock register if the ops pointer
is NULL.

Signed-off-by: Jerome Brunet <jbrunet@xxxxxxxxxxxx>
Signed-off-by: Michael Turquette <mturquette@xxxxxxxxxxxx>
Link: lkml.kernel.org/r/20171219083329.24746-1-jbrunet@xxxxxxxxxxxx
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
 drivers/clk/clk.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index b56c11f51baf..12180049a42a 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -2684,7 +2684,13 @@ struct clk *clk_register(struct device *dev, struct clk_hw *hw)
 		ret = -ENOMEM;
 		goto fail_name;
 	}
+
+	if (WARN_ON(!hw->init->ops)) {
+		ret = -EINVAL;
+		goto fail_ops;
+	}
 	core->ops = hw->init->ops;
+
 	if (dev && pm_runtime_enabled(dev))
 		core->dev = dev;
 	if (dev && dev->driver)
@@ -2746,6 +2752,7 @@ struct clk *clk_register(struct device *dev, struct clk_hw *hw)
 		kfree_const(core->parent_names[i]);
 	kfree(core->parent_names);
 fail_parent_names:
+fail_ops:
 	kfree_const(core->name);
 fail_name:
 	kfree(core);
-- 
2.14.1