linux-kernel - Re: [PATCH next] nvdimm: Prevent integer overflow in ramdax_get_config

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Message-ID: <6925db85a9343_63977100fd@iweiny-mobl.notmuch>
Date: Tue, 25 Nov 2025 10:38:29 -0600
From: Ira Weiny <ira.weiny@...el.com>
To: Dan Carpenter <dan.carpenter@...aro.org>, Mike Rapoport <rppt@...nel.org>
CC: Dan Williams <dan.j.williams@...el.com>, Vishal Verma
	<vishal.l.verma@...el.com>, Dave Jiang <dave.jiang@...el.com>, Ira Weiny
	<ira.weiny@...el.com>, <nvdimm@...ts.linux.dev>,
	<linux-kernel@...r.kernel.org>, <kernel-janitors@...r.kernel.org>
Subject: Re: [PATCH next] nvdimm: Prevent integer overflow in
 ramdax_get_config_data()

Dan Carpenter wrote:
> The "cmd->in_offset" variable comes from the user via the __nd_ioctl()
> function.  The problem is that the "cmd->in_offset + cmd->in_length"
> addition could have an integer wrapping issue if cmd->in_offset is close
> to UINT_MAX .  The "cmd->in_length" variable has been capped, but the
> "cmd->in_offset" variable has not.  Both of these variables are type u32.

Does ramdax_set_config_data() also need this?  I'm not quite following
where in_length is capped so I'm inclined to add size_add in both set and
get.

Ira

> 
> Fixes: 43bc0aa19a21 ("nvdimm: allow exposing RAM carveouts as NVDIMM DIMM devices")
> Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
> ---
>  drivers/nvdimm/ramdax.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/nvdimm/ramdax.c b/drivers/nvdimm/ramdax.c
> index 63cf05791829..faa6f3101972 100644
> --- a/drivers/nvdimm/ramdax.c
> +++ b/drivers/nvdimm/ramdax.c
> @@ -143,7 +143,7 @@ static int ramdax_get_config_data(struct nvdimm *nvdimm, int buf_len,
>  		return -EINVAL;
>  	if (struct_size(cmd, out_buf, cmd->in_length) > buf_len)
>  		return -EINVAL;
> -	if (cmd->in_offset + cmd->in_length > LABEL_AREA_SIZE)
> +	if (size_add(cmd->in_offset, cmd->in_length) > LABEL_AREA_SIZE)
>  		return -EINVAL;
>  
>  	memcpy(cmd->out_buf, dimm->label_area + cmd->in_offset, cmd->in_length);
> -- 
> 2.51.0
>