Re: [PATCH] makedumpfile: Fix the variable pfn_needed leaking

["\"Zhou, Wenjian/周文剑\"" <zhouwj-fnst@cn.fujitsu.com>]

On 11/11/2014 04:54 PM, Minfei Huang wrote:
> If the page pfn calculated by read_from_splitblock_table is bigger than
> pfn_needed, the variable pfn_needed will leak.
>
> makedumpfile cannot assign the pfn averagely bacause of condition
> pfn_needed invalid.
>
> Signed-off-by: Minfei Huang<mhuang@redhat.com>
> ---
>   makedumpfile.c | 5 +++--
>   1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/makedumpfile.c b/makedumpfile.c
> index 59c4952..8807a90 100644
> --- a/makedumpfile.c
> +++ b/makedumpfile.c
> @@ -8415,7 +8415,7 @@ calculate_end_pfn_by_splitblock(mdf_pfn_t start_pfn,
>   		return info->max_mapnr;
>
>   	mdf_pfn_t end_pfn;
> -	long long pfn_needed, offset;
> +	long long pfn_needed, offset, per_splitblock_pfn;
>   	char *splitblock_value_offset;
>
>   	pfn_needed = info->num_dumpable / info->num_dumpfile;
> @@ -8424,7 +8424,8 @@ calculate_end_pfn_by_splitblock(mdf_pfn_t start_pfn,
>   	end_pfn = start_pfn;
>
>   	while (*cur_splitblock_num<  splitblock->num&&  pfn_needed>  0) {
> -		pfn_needed -= read_from_splitblock_table(splitblock_value_offset);
> +		per_splitblock_pfn = read_from_splitblock_table(splitblock_value_offset);
> +		pfn_needed = pfn_needed<  per_splitblock_pfn ? 0 : pfn_needed - per_splitblock_pfn;
>   		splitblock_value_offset += splitblock->entry_size;
>   		++*cur_splitblock_num;
>   	}

Hello Huang,

Actually, pfn_needed is used to indicate whether the dumpfile have enough pfn or not.
It doesn't matter whether pfn_needed == 0 or pfn_needed < 0.

I know what you want to express. Maybe you can get some useful information at
http://lists.infradead.org/pipermail/kexec/2014-October/012805.html

-- 
Thanks
Zhou Wenjian

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