Re: [PATCH 4/4] mtd: rfd_ftl: fix use-after-free

[Miquel Raynal <miquel.raynal@bootlin.com>]

Hi Sean,

Sean Young <sean@mess.org> wrote on Tue, 13 Jul 2021 10:44:03 +0100:

> del_mtd_blktrans_dev() will kfree part, so this is a use-after-free. Use
> container_of() to make it clearer what the cast is doing.
> 
> Signed-off-by: Sean Young <sean@mess.org>
> ---
>  drivers/mtd/rfd_ftl.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/mtd/rfd_ftl.c b/drivers/mtd/rfd_ftl.c
> index 7f5f6d247cae..af20a0a71108 100644
> --- a/drivers/mtd/rfd_ftl.c
> +++ b/drivers/mtd/rfd_ftl.c

[...]

> @@ -800,10 +800,10 @@ static void rfd_ftl_remove_dev(struct
mtd_blktrans_dev *dev)
>  			part->mbd.mtd->name, i, part->blocks[i].erases);
>  	}
>  
> -	del_mtd_blktrans_dev(dev);
>  	vfree(part->sector_map);
>  	kfree(part->header_cache);
>  	kfree(part->blocks);
> +	del_mtd_blktrans_dev(&part->mbd);

I am not sure moving this call at the bottom of ftl_remove_dev makes
sense, can we keep it where it was and just do the s/dev/part->mbd/ ?

>  }
>  
>  static struct mtd_blktrans_ops rfd_ftl_tr = {

Thanks,
Miquèl

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