Re: [PATCH] block: set bi_vcnt when cloning bio

[John Garry <john.g.garry@oracle.com>]

On 15/02/2025 10:58, Andreas Hindborg wrote:
> When cloning a bio, the `bio.bi_vcnt` field is not cloned. This is a
> problem if users want to perform bounds checks on the `bio.bi_io_vec`
> field.

Is this fixing a potential problem? Or fixing a real issue?

Thanks,
John

> 
> Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
> ---
>   block/bio.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/block/bio.c b/block/bio.c
> index f0c416e5931d9..334eedf312803 100644
> --- a/block/bio.c
> +++ b/block/bio.c
> @@ -870,6 +870,7 @@ struct bio *bio_alloc_clone(struct block_device *bdev, struct bio *bio_src,
>   		return NULL;
>   	}
>   	bio->bi_io_vec = bio_src->bi_io_vec;
> +	bio->bi_vcnt = bio_src->bi_vcnt;
>   
>   	return bio;
>   }
> 
> ---
> base-commit: a64dcfb451e254085a7daee5fe51bf22959d52d3
> change-id: 20250215-clone-bi_vcnt-f3f770988894
> 
> Best regards,