linux-kernel - Re: [PATCH v2 1/1] scsi: ufs: Fix unexpected values get from ufshcd_read_desc

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Date:   Tue, 10 Nov 2020 14:23:57 -0800
From:   "Asutosh Das (asd)" <asutoshd@...eaurora.org>
To:     Can Guo <cang@...eaurora.org>, nguyenb@...eaurora.org,
        hongwus@...eaurora.org, rnayak@...eaurora.org,
        linux-scsi@...r.kernel.org, kernel-team@...roid.com,
        saravanak@...gle.com, salyzyn@...gle.com
Cc:     Alim Akhtar <alim.akhtar@...sung.com>,
        Avri Altman <avri.altman@....com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Stanley Chu <stanley.chu@...iatek.com>,
        Bean Huo <beanhuo@...ron.com>,
        Bart Van Assche <bvanassche@....org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/1] scsi: ufs: Fix unexpected values get from
 ufshcd_read_desc_param()

On 10/21/2020 10:59 PM, Can Guo wrote:
> Since WB feature has been added, WB related sysfs entries can be accessed
> even when an UFS device does not support WB feature. In that case, the
> descriptors which are not supported by the UFS device may be wrongly
> reported when they are accessed from their corrsponding sysfs entries.
> Fix it by adding a sanity check of parameter offset against the actual
> decriptor length.
> 
> Signed-off-by: Can Guo <cang@...eaurora.org>
> ---

Reviewed-by: Asutosh Das <asutoshd@...eaurora.org>

>   drivers/scsi/ufs/ufshcd.c | 24 +++++++++++++++---------
>   1 file changed, 15 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index a2ebcc8..aeec10d 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -3184,13 +3184,19 @@ int ufshcd_read_desc_param(struct ufs_hba *hba,
>   	/* Get the length of descriptor */
>   	ufshcd_map_desc_id_to_length(hba, desc_id, &buff_len);
>   	if (!buff_len) {
> -		dev_err(hba->dev, "%s: Failed to get desc length", __func__);
> +		dev_err(hba->dev, "%s: Failed to get desc length\n", __func__);
> +		return -EINVAL;
> +	}
> +
> +	if (param_offset >= buff_len) {
> +		dev_err(hba->dev, "%s: Invalid offset 0x%x in descriptor IDN 0x%x, length 0x%x\n",
> +			__func__, param_offset, desc_id, buff_len);
>   		return -EINVAL;
>   	}
>   
>   	/* Check whether we need temp memory */
>   	if (param_offset != 0 || param_size < buff_len) {
> -		desc_buf = kmalloc(buff_len, GFP_KERNEL);
> +		desc_buf = kzalloc(buff_len, GFP_KERNEL);
>   		if (!desc_buf)
>   			return -ENOMEM;
>   	} else {
> @@ -3204,14 +3210,14 @@ int ufshcd_read_desc_param(struct ufs_hba *hba,
>   					desc_buf, &buff_len);
>   
>   	if (ret) {
> -		dev_err(hba->dev, "%s: Failed reading descriptor. desc_id %d, desc_index %d, param_offset %d, ret %d",
> +		dev_err(hba->dev, "%s: Failed reading descriptor. desc_id %d, desc_index %d, param_offset %d, ret %d\n",
>   			__func__, desc_id, desc_index, param_offset, ret);
>   		goto out;
>   	}
>   
>   	/* Sanity check */
>   	if (desc_buf[QUERY_DESC_DESC_TYPE_OFFSET] != desc_id) {
> -		dev_err(hba->dev, "%s: invalid desc_id %d in descriptor header",
> +		dev_err(hba->dev, "%s: invalid desc_id %d in descriptor header\n",
>   			__func__, desc_buf[QUERY_DESC_DESC_TYPE_OFFSET]);
>   		ret = -EINVAL;
>   		goto out;
> @@ -3221,12 +3227,12 @@ int ufshcd_read_desc_param(struct ufs_hba *hba,
>   	buff_len = desc_buf[QUERY_DESC_LENGTH_OFFSET];
>   	ufshcd_update_desc_length(hba, desc_id, desc_index, buff_len);
>   
> -	/* Check wherher we will not copy more data, than available */
> -	if (is_kmalloc && (param_offset + param_size) > buff_len)
> -		param_size = buff_len - param_offset;
> -
> -	if (is_kmalloc)
> +	if (is_kmalloc) {
> +		/* Make sure we don't copy more data than available */
> +		if (param_offset + param_size > buff_len)
> +			param_size = buff_len - param_offset;
>   		memcpy(param_read_buf, &desc_buf[param_offset], param_size);
> +	}
>   out:
>   	if (is_kmalloc)
>   		kfree(desc_buf);
> 


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