Re: [PATCH] netfilter: account ebt_table_info to kmemcg

[Michal Hocko]

On Fri 28-12-18 17:55:24, Shakeel Butt wrote:
> The [ip,ip6,arp]_tables use x_tables_info internally and the underlying
> memory is already accounted to kmemcg. Do the same for ebtables. The
> syzbot, by using setsockopt(EBT_SO_SET_ENTRIES), was able to OOM the
> whole system from a restricted memcg, a potential DoS.

What is the lifetime of these objects? Are they bound to any process?

> Reported-by: syzbot+7713f3aa67be76b1552c@xxxxxxxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
> ---
>  net/bridge/netfilter/ebtables.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
> index 491828713e0b..5e55cef0cec3 100644
> --- a/net/bridge/netfilter/ebtables.c
> +++ b/net/bridge/netfilter/ebtables.c
> @@ -1137,14 +1137,16 @@ static int do_replace(struct net *net, const void __user *user,
>  	tmp.name[sizeof(tmp.name) - 1] = 0;
>  
>  	countersize = COUNTER_OFFSET(tmp.nentries) * nr_cpu_ids;
> -	newinfo = vmalloc(sizeof(*newinfo) + countersize);
> +	newinfo = __vmalloc(sizeof(*newinfo) + countersize, GFP_KERNEL_ACCOUNT,
> +			    PAGE_KERNEL);
>  	if (!newinfo)
>  		return -ENOMEM;
>  
>  	if (countersize)
>  		memset(newinfo->counters, 0, countersize);
>  
> -	newinfo->entries = vmalloc(tmp.entries_size);
> +	newinfo->entries = __vmalloc(tmp.entries_size, GFP_KERNEL_ACCOUNT,
> +				     PAGE_KERNEL);
>  	if (!newinfo->entries) {
>  		ret = -ENOMEM;
>  		goto free_newinfo;
> -- 
> 2.20.1.415.g653613c723-goog
> 

-- 
Michal Hocko
SUSE Labs