linux-kernel - [PATCH 4.15 55/84] clk: check ops pointer on clock register

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Date:   Fri, 23 Mar 2018 10:54:09 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jerome Brunet <jbrunet@...libre.com>,
        Michael Turquette <mturquette@...libre.com>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 4.15 55/84] clk: check ops pointer on clock register

4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jerome Brunet <jbrunet@...libre.com>


[ 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@...libre.com>
Signed-off-by: Michael Turquette <mturquette@...libre.com>
Link: lkml.kernel.org/r/20171219083329.24746-1-jbrunet@...libre.com
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/clk/clk.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -2684,7 +2684,13 @@ struct clk *clk_register(struct device *
 		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 @@ fail_parent_names_copy:
 		kfree_const(core->parent_names[i]);
 	kfree(core->parent_names);
 fail_parent_names:
+fail_ops:
 	kfree_const(core->name);
 fail_name:
 	kfree(core);