Re: [PATCH] xfs: use struct_size() helper

["Darrick J. Wong" <darrick.wong@oracle.com>]

[fixing linux-xfs cc]

On Thu, Apr 11, 2019 at 06:37:58PM -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 code of the following form:
> 
> sizeof(*alist) + context->count * sizeof(alist->al_offset[0]
> 
> with:
> 
> struct_size(alist, al_offset, context->count)
> 
> and remove unnecessary variable arraytop.
> 
> This code was detected with the help of Coccinelle.
> 
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

Has this been run through xfstests?

--D

>  fs/xfs/xfs_attr_list.c | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/fs/xfs/xfs_attr_list.c b/fs/xfs/xfs_attr_list.c
> index 3d213a7394c5..05e03348553e 100644
> --- a/fs/xfs/xfs_attr_list.c
> +++ b/fs/xfs/xfs_attr_list.c
> @@ -553,7 +553,6 @@ xfs_attr_put_listent(
>  {
>  	struct attrlist *alist = (struct attrlist *)context->alist;
>  	attrlist_ent_t *aep;
> -	int arraytop;
>  
>  	ASSERT(!context->seen_enough);
>  	ASSERT(!(context->flags & ATTR_KERNOVAL));
> @@ -572,10 +571,8 @@ xfs_attr_put_listent(
>  	    ((flags & XFS_ATTR_ROOT) == 0))
>  		return;
>  
> -	arraytop = sizeof(*alist) +
> -			context->count * sizeof(alist->al_offset[0]);
>  	context->firstu -= ATTR_ENTSIZE(namelen);
> -	if (context->firstu < arraytop) {
> +	if (context->firstu < struct_size(alist, al_offset, context->count)) {
>  		trace_xfs_attr_list_full(context);
>  		alist->al_more = 1;
>  		context->seen_enough = 1;
> -- 
> 2.21.0
>