Make use of the struct_size() helper instead of an open-coded version,
in order to avoid any potential type mistakes or integer overflows that,
in the worst scenario, could lead to heap overflows.

Also, address the following sparse warnings:
drivers/comedi/drivers/das16.c:964:45: warning: using sizeof on a flexible structure
drivers/comedi/drivers/das16.c:998:45: warning: using sizeof on a flexible structure

Link: https://github.com/KSPP/linux/issues/174
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
 drivers/comedi/drivers/das16.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/comedi/drivers/das16.c b/drivers/comedi/drivers/das16.c
index 937a69ce0977..728dc02156c8 100644
--- a/drivers/comedi/drivers/das16.c
+++ b/drivers/comedi/drivers/das16.c
@@ -961,7 +961,7 @@ static const struct comedi_lrange *das16_ai_range(struct comedi_device *dev,
 
 		/* allocate single-range range table */
 		lrange = comedi_alloc_spriv(s,
-					    sizeof(*lrange) + sizeof(*krange));
+					    struct_size(lrange, range, 1));
 		if (!lrange)
 			return &range_unknown;
 
@@ -995,7 +995,7 @@ static const struct comedi_lrange *das16_ao_range(struct comedi_device *dev,
 
 		/* allocate single-range range table */
 		lrange = comedi_alloc_spriv(s,
-					    sizeof(*lrange) + sizeof(*krange));
+					    struct_size(lrange, range, 1));
 		if (!lrange)
 			return &range_unknown;
 
-- 
2.27.0

On 25/01/2022 23:25, Gustavo A. R. Silva wrote:
> Make use of the struct_size() helper instead of an open-coded version,
> in order to avoid any potential type mistakes or integer overflows that,
> in the worst scenario, could lead to heap overflows.
> 
> Also, address the following sparse warnings:
> drivers/comedi/drivers/das16.c:964:45: warning: using sizeof on a flexible structure
> drivers/comedi/drivers/das16.c:998:45: warning: using sizeof on a flexible structure
> 
> Link: https://github.com/KSPP/linux/issues/174
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
> ---
>   drivers/comedi/drivers/das16.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/comedi/drivers/das16.c b/drivers/comedi/drivers/das16.c
> index 937a69ce0977..728dc02156c8 100644
> --- a/drivers/comedi/drivers/das16.c
> +++ b/drivers/comedi/drivers/das16.c
> @@ -961,7 +961,7 @@ static const struct comedi_lrange *das16_ai_range(struct comedi_device *dev,
>   
>   		/* allocate single-range range table */
>   		lrange = comedi_alloc_spriv(s,
> -					    sizeof(*lrange) + sizeof(*krange));
> +					    struct_size(lrange, range, 1));
>   		if (!lrange)
>   			return &range_unknown;
>   
> @@ -995,7 +995,7 @@ static const struct comedi_lrange *das16_ao_range(struct comedi_device *dev,
>   
>   		/* allocate single-range range table */
>   		lrange = comedi_alloc_spriv(s,
> -					    sizeof(*lrange) + sizeof(*krange));
> +					    struct_size(lrange, range, 1));
>   		if (!lrange)
>   			return &range_unknown;
>   

Looks like a nice tidy-up, thanks!

Reviewed-by: Ian Abbott <abbotti@mev.co.uk>

(Note, I do not have anywhere to commit it, personally.)

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