linux-kernel - [PATCH] clk: only call get

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Message-ID: <52288824.1060905@linaro.org>
Date:	Thu, 05 Sep 2013 08:33:24 -0500
From:	Alex Elder <alex.elder@...aro.org>
To:	Mike Turquette <mturquette@...aro.org>
CC:	linux-arm-kernel@...ts.infradead.org,
	LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] clk: only call get_parent if there is one

In __clk_init(), after a clock is mostly initialized, a scan is done
of the orphan clocks to see if the clock being registered is the
parent of any of them.

This code assumes that any clock that provides a get_parent method
actually has at least one parent, and that's not a valid assumption.

As a result, an orphan clock with no parent can return *something*
as the parent index, and that value is blindly used to dereference
the orphan's parent_names[] array (which will be ZERO_SIZE_PTR or
NULL).

Fix this by ensuring get_parent is only called for orphans with at
least one parent.

Signed-off-by: Alex Elder <elder@...aro.org>
---
 drivers/clk/clk.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 54a191c..ea8ff15 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -1628,7 +1628,7 @@ int __clk_init(struct device *dev, struct clk *clk)
 	 * this clock
 	 */
 	hlist_for_each_entry_safe(orphan, tmp2, &clk_orphan_list, child_node) {
-		if (orphan->ops->get_parent) {
+		if (orphan->num_parents && orphan->ops->get_parent) {
 			i = orphan->ops->get_parent(orphan->hw);
 			if (!strcmp(clk->name, orphan->parent_names[i]))
 				__clk_reparent(orphan, clk);
-- 
1.7.9.5

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