4.20-stable review patch. If anyone has any objections, please let me know.
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From: Shakeel Butt shakeelb@google.com
commit e2c8d550a973bb34fc28bc8d0ec996f84562fb8a upstream.
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: syzbot+7713f3aa67be76b1552c@syzkaller.appspotmail.com Signed-off-by: Shakeel Butt shakeelb@google.com Reviewed-by: Kirill Tkhai ktkhai@virtuozzo.com Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/bridge/netfilter/ebtables.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- a/net/bridge/netfilter/ebtables.c +++ b/net/bridge/netfilter/ebtables.c @@ -1137,14 +1137,16 @@ static int do_replace(struct net *net, c 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;