Re: [patch 11/12] sound/oss/emu10k1/* - compile warning cleanup

[Andrew Morton <akpm@osdl.org>]

domen@coderock.org wrote:
>
> 
> compile warning cleanup - handle copy_to/from_user error 
> returns

If a write() gets a fault it's supposed to return the number of bytes which
it actually wrote, which may be zero.

Still, returning -EFAULT is better than appearing to have succeeded.

> +			printk( KERN_ERR "emu10k1: %s: copy_to_user failed\n",__FUNCTION__);

Someone needs to read Documentation/CodingStyle.  I'll change these to

 printk(KERN_ERR "emu10k1: %s: copy_to_user failed\n", __FUNCTION__);

> +			return;
> +		}
> +	}
>  	else {
>  		u8 byte;
>  		u32 i;
> @@ -316,7 +320,10 @@ static void copy_block(u8 __user *dst, u
>  
>  		for (i = 0; i < len; i++) {
>  			byte = src[2 * i] ^ 0x80;
> -			__copy_to_user(dst + i, &byte, 1);
> +			if (__copy_to_user(dst + i, &byte, 1)) {
> +				printk( KERN_ERR "emu10k1: %s: copy_to_user failed\n",__FUNCTION__);
> +				return;
> +			}
>  		}
>  	}
>  }
> diff -puN sound/oss/emu10k1/passthrough.c~return_code-sound_oss_emu10k1 sound/oss/emu10k1/passthrough.c
> --- kj/sound/oss/emu10k1/passthrough.c~return_code-sound_oss_emu10k1	2005-03-05 16:13:11.000000000 +0100
> +++ kj-domen/sound/oss/emu10k1/passthrough.c	2005-03-05 16:13:11.000000000 +0100
> @@ -162,12 +162,14 @@ ssize_t emu10k1_pt_write(struct file *fi
>  
>  		DPD(3, "prepend size %d, prepending %d bytes\n", pt->prepend_size, needed);
>  		if (count < needed) {
> -			copy_from_user(pt->buf + pt->prepend_size, buffer, count);
> +			if (copy_from_user(pt->buf + pt->prepend_size, buffer, count))
> +				return -EFAULT;
>  			pt->prepend_size += count;
>  			DPD(3, "prepend size now %d\n", pt->prepend_size);
>  			return count;
>  		}
> -		copy_from_user(pt->buf + pt->prepend_size, buffer, needed);
> +		if (copy_from_user(pt->buf + pt->prepend_size, buffer, needed))
> +			return -EFAULT;
>  		r = pt_putblock(wave_dev, (u16 *) pt->buf, nonblock);
>  		if (r)
>  			return r;
> @@ -178,7 +180,8 @@ ssize_t emu10k1_pt_write(struct file *fi
>  	blocks_copied = 0;
>  	while (blocks > 0) {
>  		u16 __user *bufptr = (u16 __user *) buffer + (bytes_copied/2);
> -		copy_from_user(pt->buf, bufptr, PT_BLOCKSIZE);
> +		if (copy_from_user(pt->buf, bufptr, PT_BLOCKSIZE))
> +			return -EFAULT;
>  		r = pt_putblock(wave_dev, (u16 *)pt->buf, nonblock);
>  		if (r) {
>  			if (bytes_copied)
> @@ -193,7 +196,8 @@ ssize_t emu10k1_pt_write(struct file *fi
>  	i = count - bytes_copied;
>  	if (i) {
>  		pt->prepend_size = i;
> -		copy_from_user(pt->buf, buffer + bytes_copied, i);
> +		if (copy_from_user(pt->buf, buffer + bytes_copied, i))
> +			return -EFAULT;
>  		bytes_copied += i;
>  		DPD(3, "filling prepend buffer with %d bytes", i);
>  	}
> _