clk: only call get_parent if there is one

Message ID 522F732A.3090802@linaro.org
State New
Headers show

Commit Message

Alex Elder Sept. 10, 2013, 7:29 p.m.
-------- Original Message --------
Subject: [PATCH] clk: only call get_parent if there is one
Date: Thu, 05 Sep 2013 08:33:24 -0500
From: Alex Elder <alex.elder@linaro.org>
To: Mike Turquette <mturquette@linaro.org>
CC: linux-arm-kernel@lists.infradead.org,  LKML
<linux-kernel@vger.kernel.org>

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@linaro.org>
---
 drivers/clk/clk.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Patch

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);