Re: [PATCH][5/6]ELF format dump file access

[Andrew Morton <akpm@osdl.org>]

Hariprasad Nellitheertha <hari@in.ibm.com> wrote:
>
> +/*
> + * Reads from the oldmem device from given offset till
> + * given count
> + */
> +static ssize_t read_from_oldmem(char *buf, size_t count,
> +			     loff_t *ppos, int userbuf)
> +{
> +	unsigned long pfn, p = *ppos;
> +	size_t read = 0;
> +
> +	pfn = p / PAGE_SIZE;
> +	p = p % PAGE_SIZE;
> +
> +	if (pfn > saved_max_pfn) {
> +		read = -EINVAL;
> +		goto done;
> +	}
> +
> +	if (count > PAGE_SIZE - p)
> +		count = PAGE_SIZE - p;
> +
> +	if (copy_oldmem_page(pfn, buf, count, userbuf)) {
> +		read = -EFAULT;
> +		goto done;
> +	}
> +
> +	*ppos += count;

hm, what's going on here?  *ppos is a loff_t but you've copied it
into a 32-bit local prior to calculating the pfn.