[Patch 1/3] clk: fix clk_mux_get_parent return's signed value

From: Ambresh K
Date: Thu May 02 2013 - 02:26:15 EST


From: Ambresh K <ambresh@xxxxxx>

If for some reason, the value read from clksel field return
erroneous due to HW bug or improper configuration, then
clk_mux_get_parent should return appropriate error's.

Currently if the value read is greater than the number of
available parents clk_mux_get_parent return's signed error
which will result in NULL pointer dereferencing in the
calling functions.

Signed-off-by: Ambresh K <ambresh@xxxxxx>
---
drivers/clk/clk-mux.c | 2 +-
drivers/clk/clk.c | 12 +++++++++++-
include/linux/clk-provider.h | 4 ++--
3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/clk/clk-mux.c b/drivers/clk/clk-mux.c
index 25b1734..be0857e 100644
--- a/drivers/clk/clk-mux.c
+++ b/drivers/clk/clk-mux.c
@@ -29,7 +29,7 @@

#define to_clk_mux(_hw) container_of(_hw, struct clk_mux, hw)

-static u8 clk_mux_get_parent(struct clk_hw *hw)
+static int clk_mux_get_parent(struct clk_hw *hw)
{
struct clk_mux *mux = to_clk_mux(hw);
int num_parents = __clk_get_num_parents(hw->clk);
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 934cfd1..c187321 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -1281,7 +1281,7 @@ EXPORT_SYMBOL_GPL(clk_get_parent);
static struct clk *__clk_init_parent(struct clk *clk)
{
struct clk *ret = NULL;
- u8 index;
+ int index;

/* handle the trivial cases */

@@ -1309,6 +1309,11 @@ static struct clk *__clk_init_parent(struct clk *clk)
*/

index = clk->ops->get_parent(clk->hw);
+ if (index < 0) {
+ pr_err("%s: clk(%s) invalid parent clk_sel index(%d)\n",
+ __func__, clk->name, index);
+ goto out;
+ }

if (!clk->parents)
clk->parents =
@@ -1632,6 +1637,11 @@ int __clk_init(struct device *dev, struct clk *clk)
hlist_for_each_entry_safe(orphan, tmp2, &clk_orphan_list, child_node) {
if (orphan->ops->get_parent) {
i = orphan->ops->get_parent(orphan->hw);
+ if (i < 0) {
+ pr_err("%s: orphan clk(%s) invalid parent\n",
+ __func__, orphan->name);
+ continue;
+ }
if (!strcmp(clk->name, orphan->parent_names[i]))
__clk_reparent(orphan, clk);
continue;
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 1186098..96337a1 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -80,7 +80,7 @@ struct clk_hw;
* supported by the clock.
*
* @get_parent: Queries the hardware to determine the parent of a clock. The
- * return value is a u8 which specifies the index corresponding to
+ * return value which specifies the index corresponding to
* the parent clock. This index can be applied to either the
* .parent_names or .parents arrays. In short, this function
* translates the parent value read from hardware into an array
@@ -127,7 +127,7 @@ struct clk_ops {
long (*round_rate)(struct clk_hw *hw, unsigned long,
unsigned long *);
int (*set_parent)(struct clk_hw *hw, u8 index);
- u8 (*get_parent)(struct clk_hw *hw);
+ int (*get_parent)(struct clk_hw *hw);
int (*set_rate)(struct clk_hw *hw, unsigned long,
unsigned long);
void (*init)(struct clk_hw *hw);
--
1.7.4.1

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