[PATCH] RDMA/ucma: Use struct_size() helper

[PATCH] RDMA/ucma: Use struct_size() helper

[Gustavo A. R. Silva]

Make use of the struct_size() helper instead of an open-coded version
in order to avoid any potential type mistakes, in particular in the
context in which this code is being used.

So, replace the following form:

sizeof(*resp) + (i * sizeof(struct ib_path_rec_data))

with:

struct_size(resp, path_data, i)

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 drivers/infiniband/core/ucma.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
index 140a338a135f..cbe460076611 100644
--- a/drivers/infiniband/core/ucma.c
+++ b/drivers/infiniband/core/ucma.c
@@ -951,8 +951,7 @@ static ssize_t ucma_query_path(struct ucma_context *ctx,
 		}
 	}
 
-	if (copy_to_user(response, resp,
-			 sizeof(*resp) + (i * sizeof(struct ib_path_rec_data))))
+	if (copy_to_user(response, resp, struct_size(resp, path_data, i)))
 		ret = -EFAULT;
 
 	kfree(resp);
-- 
2.21.0

Re: [PATCH] RDMA/ucma: Use struct_size() helper

[Leon Romanovsky]

On Tue, Jun 04, 2019 at 10:42:22AM -0500, 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, in particular in the
> context in which this code is being used.

What does "in particular in the context in which this code is being
used" mean?

>
> So, replace the following form:
>
> sizeof(*resp) + (i * sizeof(struct ib_path_rec_data))
>
> with:
>
> struct_size(resp, path_data, i)

It is already written inside commit itself.

>
> This code was detected with the help of Coccinelle.
>
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> ---
>  drivers/infiniband/core/ucma.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
> index 140a338a135f..cbe460076611 100644
> --- a/drivers/infiniband/core/ucma.c
> +++ b/drivers/infiniband/core/ucma.c
> @@ -951,8 +951,7 @@ static ssize_t ucma_query_path(struct ucma_context *ctx,
>  		}
>  	}
>
> -	if (copy_to_user(response, resp,
> -			 sizeof(*resp) + (i * sizeof(struct ib_path_rec_data))))
> +	if (copy_to_user(response, resp, struct_size(resp, path_data, i)))
>  		ret = -EFAULT;
>
>  	kfree(resp);
> --
> 2.21.0
>

Re: [PATCH] RDMA/ucma: Use struct_size() helper

[Jason Gunthorpe]

On Tue, Jun 04, 2019 at 10:42:22AM -0500, 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, in particular in the
> context in which this code is being used.
> 
> So, replace the following form:
> 
> sizeof(*resp) + (i * sizeof(struct ib_path_rec_data))
> 
> with:
> 
> struct_size(resp, path_data, i)
> 
> This code was detected with the help of Coccinelle.
> 
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> ---
>  drivers/infiniband/core/ucma.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)

Applied to for-next, thanks

Jason

Re: [PATCH] RDMA/ucma: Use struct_size() helper

[Enrico Weigelt, metux IT consult]

On 04.06.19 17:42, Gustavo A. R. Silva wrote:

Hi,

<snip>

> diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
> index 140a338a135f..cbe460076611 100644
> --- a/drivers/infiniband/core/ucma.c
> +++ b/drivers/infiniband/core/ucma.c
> @@ -951,8 +951,7 @@ static ssize_t ucma_query_path(struct ucma_context *ctx,
>  		}
>  	}
>  
> -	if (copy_to_user(response, resp,
> -			 sizeof(*resp) + (i * sizeof(struct ib_path_rec_data))))
> +	if (copy_to_user(response, resp, struct_size(resp, path_data, i)))
>  		ret = -EFAULT;

have you already considered further reducing the boilerplate by putting
this into it's own helper macro, so it finally would look like this ?

+	if (copy_to_user_structs(response, resp, resp, path_data, i)))
>  		ret = -EFAULT;

You've posted similar patches that also affected things like kzalloc().
Maybe for those it would be better candidates for putting everything
into its own helper macro ? (I've already got that on my 2do list, but
not sure whether maintainers really like to be bothered with those
kind of patches ;-)).


--mtx

-- 
Enrico Weigelt, metux IT consult
Free software and Linux embedded engineering
info@metux.net -- +49-151-27565287