In ad9834_write_frequency() clk_get_rate() can return 0. In such case
ad9834_calc_freqreg() call will lead to division by zero. Checking
'if (fout > (clk_freq / 2))' doesn't protect in case of 'fout' is 0.
ad9834_write_frequency() is called from ad9834_write(), where fout is
taken from text buffer, which can contain any value.

Modify parameters checking.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 12b9d5bf76bf ("Staging: IIO: DDS: AD9833 / AD9834 driver")
Signed-off-by: Aleksandr Mishin <amishin@t-argos.ru>
---
 drivers/staging/iio/frequency/ad9834.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/iio/frequency/ad9834.c b/drivers/staging/iio/frequency/ad9834.c
index a7a5cdcc6590..9e42129f44f7 100644
--- a/drivers/staging/iio/frequency/ad9834.c
+++ b/drivers/staging/iio/frequency/ad9834.c
@@ -114,7 +114,7 @@ static int ad9834_write_frequency(struct ad9834_state *st,
 
 	clk_freq = clk_get_rate(st->mclk);
 
-	if (fout > (clk_freq / 2))
+	if (!fout || fout > (clk_freq / 2))
 		return -EINVAL;
 
 	regval = ad9834_calc_freqreg(clk_freq, fout);
-- 
2.30.2

On Wed, Jul 03, 2024 at 01:47:34PM +0300, Aleksandr Mishin wrote:
> In ad9834_write_frequency() clk_get_rate() can return 0. In such case
> ad9834_calc_freqreg() call will lead to division by zero. Checking
> 'if (fout > (clk_freq / 2))' doesn't protect in case of 'fout' is 0.
> ad9834_write_frequency() is called from ad9834_write(), where fout is
> taken from text buffer, which can contain any value.
> 
> Modify parameters checking.
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Fixes: 12b9d5bf76bf ("Staging: IIO: DDS: AD9833 / AD9834 driver")
> Signed-off-by: Aleksandr Mishin <amishin@t-argos.ru>
> ---
>  drivers/staging/iio/frequency/ad9834.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/iio/frequency/ad9834.c b/drivers/staging/iio/frequency/ad9834.c
> index a7a5cdcc6590..9e42129f44f7 100644
> --- a/drivers/staging/iio/frequency/ad9834.c
> +++ b/drivers/staging/iio/frequency/ad9834.c
> @@ -114,7 +114,7 @@ static int ad9834_write_frequency(struct ad9834_state *st,
>  
>  	clk_freq = clk_get_rate(st->mclk);
>  
> -	if (fout > (clk_freq / 2))
> +	if (!fout || fout > (clk_freq / 2))

So you don't want "clk_freq" to be zero so you check if "fout" can be
zero and do the algebra?  That's a lot of acrobatics.  Just check
if clk_freq == 0 directly.

regards,
dan carpenter

>  		return -EINVAL;
>  
>  	regval = ad9834_calc_freqreg(clk_freq, fout);
> -- 
> 2.30.2
>

In ad9834_write_frequency() clk_get_rate() can return 0. In such case
ad9834_calc_freqreg() call will lead to division by zero. Checking
'if (fout > (clk_freq / 2))' doesn't protect in case of 'fout' is 0.
ad9834_write_frequency() is called from ad9834_write(), where fout is
taken from text buffer, which can contain any value.

Modify parameters checking.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 12b9d5bf76bf ("Staging: IIO: DDS: AD9833 / AD9834 driver")
Suggested-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Aleksandr Mishin <amishin@t-argos.ru>
---
v1->v2: Check if clk_freq == 0 directly instead of fout == 0
 as suggested by Dan

 drivers/staging/iio/frequency/ad9834.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/iio/frequency/ad9834.c b/drivers/staging/iio/frequency/ad9834.c
index a7a5cdcc6590..47e7d7e6d920 100644
--- a/drivers/staging/iio/frequency/ad9834.c
+++ b/drivers/staging/iio/frequency/ad9834.c
@@ -114,7 +114,7 @@ static int ad9834_write_frequency(struct ad9834_state *st,
 
 	clk_freq = clk_get_rate(st->mclk);
 
-	if (fout > (clk_freq / 2))
+	if (!clk_freq || fout > (clk_freq / 2))
 		return -EINVAL;
 
 	regval = ad9834_calc_freqreg(clk_freq, fout);
-- 
2.30.2

On Wed, Jul 03, 2024 at 06:45:06PM +0300, Aleksandr Mishin wrote:
> In ad9834_write_frequency() clk_get_rate() can return 0. In such case
> ad9834_calc_freqreg() call will lead to division by zero. Checking
> 'if (fout > (clk_freq / 2))' doesn't protect in case of 'fout' is 0.
> ad9834_write_frequency() is called from ad9834_write(), where fout is
> taken from text buffer, which can contain any value.
> 
> Modify parameters checking.
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Fixes: 12b9d5bf76bf ("Staging: IIO: DDS: AD9833 / AD9834 driver")
> Suggested-by: Dan Carpenter <dan.carpenter@linaro.org>
> Signed-off-by: Aleksandr Mishin <amishin@t-argos.ru>
> ---
> v1->v2: Check if clk_freq == 0 directly instead of fout == 0
>  as suggested by Dan


Thanks!

Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>

regards,
dan carpenter

On Wed, 3 Jul 2024 18:29:43 +0200
Dan Carpenter <dan.carpenter@linaro.org> wrote:

> On Wed, Jul 03, 2024 at 06:45:06PM +0300, Aleksandr Mishin wrote:
> > In ad9834_write_frequency() clk_get_rate() can return 0. In such case
> > ad9834_calc_freqreg() call will lead to division by zero. Checking
> > 'if (fout > (clk_freq / 2))' doesn't protect in case of 'fout' is 0.
> > ad9834_write_frequency() is called from ad9834_write(), where fout is
> > taken from text buffer, which can contain any value.
> > 
> > Modify parameters checking.
> > 
> > Found by Linux Verification Center (linuxtesting.org) with SVACE.
> > 
> > Fixes: 12b9d5bf76bf ("Staging: IIO: DDS: AD9833 / AD9834 driver")
> > Suggested-by: Dan Carpenter <dan.carpenter@linaro.org>
> > Signed-off-by: Aleksandr Mishin <amishin@t-argos.ru>
> > ---
> > v1->v2: Check if clk_freq == 0 directly instead of fout == 0
> >  as suggested by Dan  
> 
> 
> Thanks!
> 
> Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>
> 
Applied and marked for stable.

> regards,
> dan carpenter
>