linux-kernel - Re: [PATCH] block: bio: Use struct

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Message-ID: <b5585d47-d126-a13c-3d2b-47cf6e33cd97@kernel.dk>
Date:   Sat, 15 Jun 2019 01:45:43 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH] block: bio: Use struct_size() in kmalloc()

On 6/10/19 9:04 AM, Gustavo A. R. Silva wrote:
> One of the more common cases of allocation size calculations is finding
> the size of a structure that has a zero-sized array at the end, along
> with memory for some number of elements for that array. For example:
> 
> struct bio_map_data {
> 	...
>          struct iovec iov[];
> };
> 
> instance = kmalloc(sizeof(sizeof(struct bio_map_data) + sizeof(struct iovec) *
>                            count, GFP_KERNEL);
> 
> Instead of leaving these open-coded and prone to type mistakes, we can
> now use the new struct_size() helper:
> 
> instance = kmalloc(struct_size(instance, iov, count), GFP_KERNEL);
> 
> This code was detected with the help of Coccinelle.

Applied, thanks.

-- 
Jens Axboe