2013-10-20 07:49:10

by Haojian Zhuang

Subject: [PATCH] clk: mux: fix the return value of get_parent

If there're no parents on the clock mux node, it should return 0, not an
errnor code.

The orphan clock node is using get_parent() to get the index of its
parents in__clk_init(). If the return value is negative, it'll be
transformed to a u8 value (clk_mux_get_parent()). Then the orphan clock
node tries to get its parent with the invalid index. It will only cause
accessing memory beyond border.

Signed-off-by: Haojian Zhuang <[email protected]>
---
drivers/clk/clk-mux.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/clk-mux.c b/drivers/clk/clk-mux.c
index 4f96ff3..cc06015 100644
--- a/drivers/clk/clk-mux.c
+++ b/drivers/clk/clk-mux.c
@@ -51,7 +51,7 @@ static u8 clk_mux_get_parent(struct clk_hw *hw)
for (i = 0; i < num_parents; i++)
if (mux->table[i] == val)
return i;
- return -EINVAL;
+ return 0;
}

if (val && (mux->flags & CLK_MUX_INDEX_BIT))
@@ -61,7 +61,7 @@ static u8 clk_mux_get_parent(struct clk_hw *hw)
val--;

if (val >= num_parents)
- return -EINVAL;
+ return 0;

return val;
}
--
1.8.1.2

2013-10-30 19:46:43

by Mike Turquette

Subject: Re: [PATCH] clk: mux: fix the return value of get_parent

Quoting Haojian Zhuang (2013-10-20 00:48:55)
> If there're no parents on the clock mux node, it should return 0, not an
> errnor code.
>
> The orphan clock node is using get_parent() to get the index of its
> parents in__clk_init(). If the return value is negative, it'll be
> transformed to a u8 value (clk_mux_get_parent()). Then the orphan clock
> node tries to get its parent with the invalid index. It will only cause
> accessing memory beyond border.
>
> Signed-off-by: Haojian Zhuang <[email protected]>

Taken into clk-next.

Thanks!
Mike

> ---
> drivers/clk/clk-mux.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/clk/clk-mux.c b/drivers/clk/clk-mux.c
> index 4f96ff3..cc06015 100644
> --- a/drivers/clk/clk-mux.c
> +++ b/drivers/clk/clk-mux.c
> @@ -51,7 +51,7 @@ static u8 clk_mux_get_parent(struct clk_hw *hw)
> for (i = 0; i < num_parents; i++)
> if (mux->table[i] == val)
> return i;
> - return -EINVAL;
> + return 0;
> }
>
> if (val && (mux->flags & CLK_MUX_INDEX_BIT))
> @@ -61,7 +61,7 @@ static u8 clk_mux_get_parent(struct clk_hw *hw)
> val--;
>
> if (val >= num_parents)
> - return -EINVAL;
> + return 0;
>
> return val;
> }
> --
> 1.8.1.2