[PATCH] clk: check for invalid parent index of orphans in __clk_init()

From: Mans Rullgard
Date: Sun Feb 15 2015 - 07:34:33 EST

If a mux clock is initialised (by hardware or firmware) with an
invalid parent, its ->get_parent() can return an out of range
index. For example, the generic mux clock attempts to return
-EINVAL, which due to the u8 return type ends up a rather large
number. Using this index with the parent_names[] array results
in an invalid pointer and (usually) a crash in the following

This patch adds a check for the parent index being in range,
ignoring clocks reporting invalid values.

Signed-off-by: Mans Rullgard <mans@xxxxxxxxx>
Cc: Rhyland Klein <rklein@xxxxxxxxxx>
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 d48ac71..bc0662b 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -1950,7 +1950,8 @@ int __clk_init(struct device *dev, struct clk *clk)
hlist_for_each_entry_safe(orphan, tmp2, &clk_orphan_list, child_node) {
if (orphan->num_parents && orphan->ops->get_parent) {
i = orphan->ops->get_parent(orphan->hw);
- if (!strcmp(clk->name, orphan->parent_names[i]))
+ if (i >= 0 && i < orphan->num_parents &&
+ !strcmp(clk->name, orphan->parent_names[i]))
__clk_reparent(orphan, clk);

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