# Re: \[patch\] fbmem: return -EFAULT on copy\_to\_user() failure

- From: Tomi Valkeinen \<hidden\>
- Date: 2013-06-26 13:04:17 
- List: linux-fbdev
- Page: https://ratatoskr.run/linux-fbdev/2013/06/4073578
- Thread: https://ratatoskr.run/linux-fbdev/2013/06/4068089/t.md

```text
On 18/06/13 10:05, Dan Carpenter wrote:
> copy_to_user() returns the number of bytes remaining to be copied.
> put_user() returns -EFAULT on error.
> 
> This function ORs a bunch of stuff together and returns jumbled non-zero
> values on error.  It should return -EFAULT.
> 
> Signed-off-by: Dan Carpenter <redacted>
> 
> diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
> index 098bfc6..9217be3 100644
> --- a/drivers/video/fbmem.c
> +++ b/drivers/video/fbmem.c
> @@ -1305,7 +1305,9 @@ static int do_fscreeninfo_to_user(struct fb_fix_screeninfo *fix,
>  	err |= copy_to_user(fix32->reserved, fix->reserved,
>  			    sizeof(fix->reserved));
>  
> -	return err;
> +	if (err)
> +		return -EFAULT;
> +	return 0;
>  }
>  
>  static int fb_get_fscreeninfo(struct fb_info *info, unsigned int cmd,

I've added this to fbdev-3.11 branch.

 Tomi



```

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