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); > 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; >
