On 06.01.2019 14:00, Kirill Tkhai wrote:
> On 03.01.2019 06:14, 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.
>>
>> By accounting the ebt_table_info, the memory used for ebt_table_info can
>> be contained within the memcg of the allocating process. However the
>> lifetime of ebt_table_info is independent of the allocating process and
>> is tied to the network namespace. So, the oom-killer will not be able to
>> relieve the memory pressure due to ebt_table_info memory. The memory for
>> ebt_table_info is allocated through vmalloc. Currently vmalloc does not
>> handle the oom-killed allocating process correctly and one large
>> allocation can bypass memcg limit enforcement. So, with this patch,
>> at least the small allocations will be contained. For large allocations,
>> we need to fix vmalloc.
>>
>> Reported-by: [email protected]
>> Signed-off-by: Shakeel Butt <[email protected]>
>> Cc: Florian Westphal <[email protected]>
>> Cc: Michal Hocko <[email protected]>
>> Cc: Kirill Tkhai <[email protected]>
>> Cc: Pablo Neira Ayuso <[email protected]>
>> Cc: Jozsef Kadlecsik <[email protected]>
>> Cc: Roopa Prabhu <[email protected]>
>> Cc: Nikolay Aleksandrov <[email protected]>
>> Cc: Andrew Morton <[email protected]>
>> Cc: Linux MM <[email protected]>
>> Cc: [email protected]
>> Cc: [email protected]
>> Cc: [email protected]
>> Cc: LKML <[email protected]>
>> ---
>> Changelog since v1:
>> - More descriptive commit message.
>
> Reviewed-by: Kirill Tkhai <[email protected]>
>
>>
>> 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);
Do we need GFP_HIGHMEM here?
>> 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;
>>
>
