[PATCH] clk: clk-axi-clkgen: fix division by zero in axi_clkgen_calc_params()

[PATCH] clk: clk-axi-clkgen: fix division by zero in axi_clkgen_calc_params()

[Zicheng Qu]

In the axi_clkgen_set_rate() function, parameters fin and fout are
checked in advance to ensure they are not equal to zero. However, in the
axi_clkgen_calc_params() function, they might become zero after /= 1000.
This could lead to a division by zero error when calculating
fvco_max_fract * d_max / fin or DIV_ROUND_CLOSEST(fvco, fout). The same
issue occurs in the axi_clkgen_determine_rate() function, where there
is no check to ensure they are non-zero.

Fixes: 0e646c52cf0e ("clk: Add axi-clkgen driver")
Cc: <stable@vger.kernel.org>
Signed-off-by: Zicheng Qu <quzicheng@huawei.com>
---
 drivers/clk/clk-axi-clkgen.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/clk-axi-clkgen.c b/drivers/clk/clk-axi-clkgen.c
index bf4d8ddc93ae..369b15a2660e 100644
--- a/drivers/clk/clk-axi-clkgen.c
+++ b/drivers/clk/clk-axi-clkgen.c
@@ -344,7 +344,7 @@ static int axi_clkgen_set_rate(struct clk_hw *clk_hw,
 	uint32_t filter;
 	uint32_t lock;
 
-	if (parent_rate == 0 || rate == 0)
+	if (parent_rate < 1000 || rate < 1000)
 		return -EINVAL;
 
 	axi_clkgen_calc_params(limits, parent_rate, rate, &d, &m, &dout);
@@ -392,6 +392,9 @@ static int axi_clkgen_determine_rate(struct clk_hw *hw,
 	unsigned int d, m, dout;
 	unsigned long long tmp;
 
+	if (req->best_parent_rate < 1000 || req->rate < 1000)
+		return -EINVAL;
+
 	axi_clkgen_calc_params(limits, req->best_parent_rate, req->rate,
 			       &d, &m, &dout);
 
-- 
2.34.1

Re: [PATCH] clk: clk-axi-clkgen: fix division by zero in axi_clkgen_calc_params()

[Zicheng Qu]

Gentle ping.

Re: [PATCH] clk: clk-axi-clkgen: fix division by zero in axi_clkgen_calc_params()

[Zicheng Qu]

Gentle ping.

On 2024/10/26 15:23, Zicheng Qu wrote:
> In the axi_clkgen_set_rate() function, parameters fin and fout are
> checked in advance to ensure they are not equal to zero. However, in the
> axi_clkgen_calc_params() function, they might become zero after /= 1000.
> This could lead to a division by zero error when calculating
> fvco_max_fract * d_max / fin or DIV_ROUND_CLOSEST(fvco, fout). The same
> issue occurs in the axi_clkgen_determine_rate() function, where there
> is no check to ensure they are non-zero.
>
> Fixes: 0e646c52cf0e ("clk: Add axi-clkgen driver")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Zicheng Qu <quzicheng@huawei.com>
> ---
>   drivers/clk/clk-axi-clkgen.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/clk/clk-axi-clkgen.c b/drivers/clk/clk-axi-clkgen.c
> index bf4d8ddc93ae..369b15a2660e 100644
> --- a/drivers/clk/clk-axi-clkgen.c
> +++ b/drivers/clk/clk-axi-clkgen.c
> @@ -344,7 +344,7 @@ static int axi_clkgen_set_rate(struct clk_hw *clk_hw,
>   	uint32_t filter;
>   	uint32_t lock;
>   
> -	if (parent_rate == 0 || rate == 0)
> +	if (parent_rate < 1000 || rate < 1000)
>   		return -EINVAL;
>   
>   	axi_clkgen_calc_params(limits, parent_rate, rate, &d, &m, &dout);
> @@ -392,6 +392,9 @@ static int axi_clkgen_determine_rate(struct clk_hw *hw,
>   	unsigned int d, m, dout;
>   	unsigned long long tmp;
>   
> +	if (req->best_parent_rate < 1000 || req->rate < 1000)
> +		return -EINVAL;
> +
>   	axi_clkgen_calc_params(limits, req->best_parent_rate, req->rate,
>   			       &d, &m, &dout);
>