linux-kernel - Re: [PATCHv2 22/28] cxusb: treat firmware data as const

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Date:	Sun, 25 May 2008 10:14:14 -0400
From:	Michael Krufky <mkrufky@...uxtv.org>
To:	David Woodhouse <dwmw2@...radead.org>
CC:	linux-kernel@...r.kernel.org, sam@...nborg.org,
	alan@...rguk.ukuu.org.uk, akpm@...ux-foundation.org,
	Patrick Boettcher <patrick.boettcher@...y.de>,
	Chris Pascoe <c.pascoe@...e.uq.edu.au>
Subject: Re: [PATCHv2 22/28] cxusb: treat firmware data as const

David,

It's broken...  Please see fix, below:

David Woodhouse wrote:
> ...which means allocating our own copy when we want to modify it.
>
> Signed-off-by: David Woodhouse <dwmw2@...radead.org>
> ---
>  drivers/media/dvb/dvb-usb/cxusb.c |   21 ++++++++++++++++++---
>  1 files changed, 18 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/media/dvb/dvb-usb/cxusb.c b/drivers/media/dvb/dvb-usb/cxusb.c
> index 720fcd1..94bb482 100644
> --- a/drivers/media/dvb/dvb-usb/cxusb.c
> +++ b/drivers/media/dvb/dvb-usb/cxusb.c
> @@ -24,6 +24,7 @@
>   * see Documentation/dvb/README.dvb-usb for more information
>   */
>  #include <media/tuner.h>
> +#include <linux/vmalloc.h>
>  
>  #include "cxusb.h"
>  
> @@ -700,12 +701,26 @@ static int bluebird_patch_dvico_firmware_download(struct usb_device *udev,
>  
>  		if (fw->data[idoff] == (USB_VID_DVICO & 0xff) &&
>  		    fw->data[idoff + 1] == USB_VID_DVICO >> 8) {
> -			fw->data[idoff + 2] =
> +			struct firmware new_fw;
> +			u8 *new_fw_data = vmalloc(fw->size);
> +			int ret;
> +
> +			if (!new_fw_data)
> +				return -ENOMEM;
> +
> +			memcpy(new_fw_data, fw->data, fw->size);
> +			new_fw.size = fw->size;
> +			new_fw.data = fw->data;
> +
> +			new_fw_data[idoff + 2] =
>  				le16_to_cpu(udev->descriptor.idProduct) + 1;
> -			fw->data[idoff + 3] =
> +			new_fw_data[idoff + 3] =
>  				le16_to_cpu(udev->descriptor.idProduct) >> 8;
>  
> -			return usb_cypress_load_firmware(udev, fw, CYPRESS_FX2);
> +			ret = usb_cypress_load_firmware(udev, &new_fw,
> +							CYPRESS_FX2);
> +			vfree(new_fw_data);
> +			return ret;
>  		}
>  	}
>  
>   
The unmodified firmware was being uploaded to the device, instead of the patched firmware :-(

After making this additional one-line change, the patch works fine.

Please feel free to fold this into your own patch.

Signed-off-by: Michael Krufky <mkrufky@...uxtv.org>

---
 linux/drivers/media/dvb/dvb-usb/cxusb.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/media/dvb/dvb-usb/cxusb.c
+++ b/drivers/media/dvb/dvb-usb/cxusb.c
@@ -710,7 +710,7 @@
 
 			memcpy(new_fw_data, fw->data, fw->size);
 			new_fw.size = fw->size;
-			new_fw.data = fw->data;
+			new_fw.data = new_fw_data;
 
 			new_fw_data[idoff + 2] =
 				le16_to_cpu(udev->descriptor.idProduct) + 1;






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