[PATCH] mtd: nand: sunxi: fix potential divide-by-zero error

[PATCH] mtd: nand: sunxi: fix potential divide-by-zero error

[Bryan O'Donoghue]

clk_round_rate() can return <= 0. Currently the value returned by
clk_round_rate() is used directly for a division. This patch introduces a
guard to ensure a divide-by-zero or a divide by a negative number for that
matter can't happen by bugging out returning -EINVAL if clk_round_rate()
returns <= 0.

Fixes: 2d43457f79e4 ("mtd: nand: sunxi: fix EDO mode selection")

Signed-off-by: Bryan O'Donoghue <pure.logic@nexus-software.ie>
---
 drivers/mtd/nand/sunxi_nand.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/mtd/nand/sunxi_nand.c b/drivers/mtd/nand/sunxi_nand.c
index d0b6f8f..6abd142 100644
--- a/drivers/mtd/nand/sunxi_nand.c
+++ b/drivers/mtd/nand/sunxi_nand.c
@@ -1728,6 +1728,10 @@ static int sunxi_nfc_setup_data_interface(struct mtd_info *mtd, int csline,
 	 */
 	chip->clk_rate = NSEC_PER_SEC / min_clk_period;
 	real_clk_rate = clk_round_rate(nfc->mod_clk, chip->clk_rate);
+	if (real_clk_rate <= 0) {
+		dev_err(nfc->dev, "Unable to round clk %lu\n", chip->clk_rate);
+		return -EINVAL;
+	}
 
 	/*
 	 * ONFI specification 3.1, paragraph 4.15.2 dictates that EDO data
-- 
2.7.4

[PATCH] mtd: nand: sunxi: fix potential divide-by-zero error

[Boris Brezillon]

On Fri, 28 Jul 2017 14:22:57 +0100
Bryan O'Donoghue <pure.logic@nexus-software.ie> wrote:

> clk_round_rate() can return <= 0. Currently the value returned by
> clk_round_rate() is used directly for a division. This patch introduces a
> guard to ensure a divide-by-zero or a divide by a negative number for that
> matter can't happen by bugging out returning -EINVAL if clk_round_rate()
> returns <= 0.

Applied to nand/fixes.

Thanks,

Boris

> 
> Fixes: 2d43457f79e4 ("mtd: nand: sunxi: fix EDO mode selection")
> 
> Signed-off-by: Bryan O'Donoghue <pure.logic@nexus-software.ie>
> ---
>  drivers/mtd/nand/sunxi_nand.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/mtd/nand/sunxi_nand.c b/drivers/mtd/nand/sunxi_nand.c
> index d0b6f8f..6abd142 100644
> --- a/drivers/mtd/nand/sunxi_nand.c
> +++ b/drivers/mtd/nand/sunxi_nand.c
> @@ -1728,6 +1728,10 @@ static int sunxi_nfc_setup_data_interface(struct mtd_info *mtd, int csline,
>  	 */
>  	chip->clk_rate = NSEC_PER_SEC / min_clk_period;
>  	real_clk_rate = clk_round_rate(nfc->mod_clk, chip->clk_rate);
> +	if (real_clk_rate <= 0) {
> +		dev_err(nfc->dev, "Unable to round clk %lu\n", chip->clk_rate);
> +		return -EINVAL;
> +	}
>  
>  	/*
>  	 * ONFI specification 3.1, paragraph 4.15.2 dictates that EDO data