2019-05-31 18:49:18

by Gustavo A. R. Silva

Subject: [PATCH] block: genhd: Use struct_size() helper

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(*new_ptbl) + target * sizeof(new_ptbl->part[0])

with:

struct_size(new_ptbl, part, target)

Also, notice that variable size is unnecessary, hence it is removed.

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <[email protected]>
---
block/genhd.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/block/genhd.c b/block/genhd.c
index ad6826628e79..c674d9090f40 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1281,7 +1281,6 @@ int disk_expand_part_tbl(struct gendisk *disk, int partno)
struct disk_part_tbl *new_ptbl;
int len = old_ptbl ? old_ptbl->len : 0;
int i, target;
- size_t size;

/*
* check for int overflow, since we can get here from blkpg_ioctl()
@@ -1298,8 +1297,8 @@ int disk_expand_part_tbl(struct gendisk *disk, int partno)
if (target <= len)
return 0;

- size = sizeof(*new_ptbl) + target * sizeof(new_ptbl->part[0]);
- new_ptbl = kzalloc_node(size, GFP_KERNEL, disk->node_id);
+ new_ptbl = kzalloc_node(struct_size(new_ptbl, part, target), GFP_KERNEL,
+ disk->node_id);
if (!new_ptbl)
return -ENOMEM;

--
2.21.0

2019-06-15 07:48:36

by Jens Axboe

Subject: Re: [PATCH] block: genhd: Use struct_size() helper

On 5/31/19 12:47 PM, 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(*new_ptbl) + target * sizeof(new_ptbl->part[0])
>
> with:
>
> struct_size(new_ptbl, part, target)
>
> Also, notice that variable size is unnecessary, hence it is removed.
>
> This code was detected with the help of Coccinelle.

Applied, thanks.

--
Jens Axboe