2017-07-28 13:16:26

by Bryan O'Donoghue

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

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 <[email protected]>
---
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

2017-07-31 16:28:48

by Boris Brezillon

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

On Fri, 28 Jul 2017 14:22:57 +0100
Bryan O'Donoghue <[email protected]> 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 <[email protected]>
> ---
> 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