linux-kernel - Re: [PATCH v6] usb-storage: alauda: Check whether the media is initialized

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Message-ID: <8176c55f-980c-4dcb-9e17-8c9c948ce216@suse.com>
Date: Mon, 27 May 2024 17:01:13 +0200
From: Oliver Neukum <oneukum@...e.com>
To: Shichao Lai <shichaorai@...il.com>, stern@...land.harvard.edu,
 gregkh@...uxfoundation.org, Markus.Elfring@....de
Cc: oneukum@...e.com, linux-usb@...r.kernel.org,
 usb-storage@...ts.one-eyed-alien.net, linux-kernel@...r.kernel.org,
 xingwei lee <xrivendell7@...il.com>, yue sun <samsun1006219@...il.com>
Subject: Re: [PATCH v6] usb-storage: alauda: Check whether the media is
 initialized

On 26.05.24 03:27, Shichao Lai wrote:

Hi,


> The member "uzonesize" of struct alauda_info will remain 0
> if alauda_init_media() fails, potentially causing divide errors
> in alauda_read_data() and alauda_write_lba().

This means that we can reach those functions.

> - Add a member "media_initialized" to struct alauda_info.
> - Change a condition in alauda_check_media() to ensure the
>    first initialization.
> - Add an error check for the return value of alauda_init_media().
> 
> Fixes: e80b0fade09e ("[PATCH] USB Storage: add alauda support")
> Reported-by: xingwei lee <xrivendell7@...il.com>
> Reported-by: yue sun <samsun1006219@...il.com>
> Reviewed-by: Alan Stern <stern@...land.harvard.edu>
> Signed-off-by: Shichao Lai <shichaorai@...il.com>
> ---
> Changes since v5:
> - Check the initialization of alauda_check_media()
>    which is the root cause.
> 
>   drivers/usb/storage/alauda.c | 9 ++++++---
>   1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/usb/storage/alauda.c b/drivers/usb/storage/alauda.c
> index 115f05a6201a..40d34cc28344 100644
> --- a/drivers/usb/storage/alauda.c
> +++ b/drivers/usb/storage/alauda.c
> @@ -105,6 +105,8 @@ struct alauda_info {
>   	unsigned char sense_key;
>   	unsigned long sense_asc;	/* additional sense code */
>   	unsigned long sense_ascq;	/* additional sense code qualifier */
> +
> +	bool media_initialized;
>   };
>   
>   #define short_pack(lsb,msb) ( ((u16)(lsb)) | ( ((u16)(msb))<<8 ) )
> @@ -476,11 +478,12 @@ static int alauda_check_media(struct us_data *us)
>   	}
>   
>   	/* Check for media change */
> -	if (status[0] & 0x08) {
> +	if (status[0] & 0x08 || !info->media_initialized) {

If we take this branch due to !info->media_initialized and only due
to this condition, alauda_check_media() will return an error

(Quoting the current state):
         /* Check for media change */
         if (status[0] & 0x08) {
                 usb_stor_dbg(us, "Media change detected\n");
                 alauda_free_maps(&MEDIA_INFO(us));
                 alauda_init_media(us);

                 info->sense_key = UNIT_ATTENTION;
                 info->sense_asc = 0x28;
                 info->sense_ascq = 0x00;
                 return USB_STOR_TRANSPORT_FAILED;

>   		usb_stor_dbg(us, "Media change detected\n");
>   		alauda_free_maps(&MEDIA_INFO(us));
> -		alauda_init_media(us);
> -
> +		rc = alauda_init_media(us);
> +		if (rc == USB_STOR_TRANSPORT_GOOD)
> +			info->media_initialized = true;
>   		info->sense_key = UNIT_ATTENTION;
>   		info->sense_asc = 0x28;
>   		info->sense_ascq = 0x00;

It seems to that we need to evaluate the reasons for taking this branch
and the result of alauda_init_media() to compute the correct return
of this function.

	Regards
		Oliver