2020-09-16 19:46:07

by Evgeny Novikov

Subject: [PATCH] mtd: rawnand: mtk: avoid underflow in mtk_nfc_nand_chip_init()

If of_get_property() will set nsels to negative values the driver may
allocate insufficient memory for chip. Moreover, there may be underflow
for devm_kzalloc(). This can result in various bad consequences later.
The patch causes mtk_nfc_nand_chip_init() to fail for negative values of
nsels.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Evgeny Novikov <[email protected]>
---
drivers/mtd/nand/raw/mtk_nand.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mtd/nand/raw/mtk_nand.c b/drivers/mtd/nand/raw/mtk_nand.c
index ad1b55dab211..df98a2eec240 100644
--- a/drivers/mtd/nand/raw/mtk_nand.c
+++ b/drivers/mtd/nand/raw/mtk_nand.c
@@ -1376,7 +1376,7 @@ static int mtk_nfc_nand_chip_init(struct device *dev, struct mtk_nfc *nfc,
return -ENODEV;

nsels /= sizeof(u32);
- if (!nsels || nsels > MTK_NAND_MAX_NSELS) {
+ if (nsels <= 0 || nsels > MTK_NAND_MAX_NSELS) {
dev_err(dev, "invalid reg property size %d\n", nsels);
return -EINVAL;
}
--
2.26.2

2020-09-17 17:33:05

by Miquel Raynal

Subject: Re: [PATCH] mtd: rawnand: mtk: avoid underflow in mtk_nfc_nand_chip_init()

Hi Evgeny,

Evgeny Novikov <[email protected]> wrote on Wed, 16 Sep 2020 22:40:45
+0300:

> If of_get_property() will set nsels to negative values the driver may

Is this really a possible case?

Looking at the OF code, I don't think it can ever happen...

> allocate insufficient memory for chip. Moreover, there may be underflow
> for devm_kzalloc(). This can result in various bad consequences later.
> The patch causes mtk_nfc_nand_chip_init() to fail for negative values of
> nsels.
>
> Found by Linux Driver Verification project (linuxtesting.org).
>
> Signed-off-by: Evgeny Novikov <[email protected]>
> ---
> drivers/mtd/nand/raw/mtk_nand.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/mtd/nand/raw/mtk_nand.c b/drivers/mtd/nand/raw/mtk_nand.c
> index ad1b55dab211..df98a2eec240 100644
> --- a/drivers/mtd/nand/raw/mtk_nand.c
> +++ b/drivers/mtd/nand/raw/mtk_nand.c
> @@ -1376,7 +1376,7 @@ static int mtk_nfc_nand_chip_init(struct device *dev, struct mtk_nfc *nfc,
> return -ENODEV;
>
> nsels /= sizeof(u32);
> - if (!nsels || nsels > MTK_NAND_MAX_NSELS) {
> + if (nsels <= 0 || nsels > MTK_NAND_MAX_NSELS) {
> dev_err(dev, "invalid reg property size %d\n", nsels);
> return -EINVAL;
> }

Thanks,
Miquèl