From: Florian Westphal fw@strlen.de
commit 3b48300d5cc7c7bed63fddb006c4046549ed4aec upstream.
ebtables doesn't include the base chain policies in the rule count, so we need to add them manually when we call into the x_tables core to allocate space for the comapt offset table.
This lead syzbot to trigger: WARNING: CPU: 1 PID: 9012 at net/netfilter/x_tables.c:649 xt_compat_add_offset.cold+0x11/0x36 net/netfilter/x_tables.c:649
Reported-by: syzbot+276ddebab3382bbf72db@syzkaller.appspotmail.com Fixes: 2035f3ff8eaa ("netfilter: ebtables: compat: un-break 32bit setsockopt when no rules are present") Signed-off-by: Florian Westphal fw@strlen.de Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/bridge/netfilter/ebtables.c | 28 +++++++++++++++++----------- 1 file changed, 17 insertions(+), 11 deletions(-)
--- a/net/bridge/netfilter/ebtables.c +++ b/net/bridge/netfilter/ebtables.c @@ -1779,20 +1779,28 @@ static int compat_calc_entry(const struc return 0; }
+static int ebt_compat_init_offsets(unsigned int number) +{ + if (number > INT_MAX) + return -EINVAL; + + /* also count the base chain policies */ + number += NF_BR_NUMHOOKS; + + return xt_compat_init_offsets(NFPROTO_BRIDGE, number); +}
static int compat_table_info(const struct ebt_table_info *info, struct compat_ebt_replace *newinfo) { unsigned int size = info->entries_size; const void *entries = info->entries; + int ret;
newinfo->entries_size = size; - if (info->nentries) { - int ret = xt_compat_init_offsets(NFPROTO_BRIDGE, - info->nentries); - if (ret) - return ret; - } + ret = ebt_compat_init_offsets(info->nentries); + if (ret) + return ret;
return EBT_ENTRY_ITERATE(entries, size, compat_calc_entry, info, entries, newinfo); @@ -2241,11 +2249,9 @@ static int compat_do_replace(struct net
xt_compat_lock(NFPROTO_BRIDGE);
- if (tmp.nentries) { - ret = xt_compat_init_offsets(NFPROTO_BRIDGE, tmp.nentries); - if (ret < 0) - goto out_unlock; - } + ret = ebt_compat_init_offsets(tmp.nentries); + if (ret < 0) + goto out_unlock;
ret = compat_copy_entries(entries_tmp, tmp.entries_size, &state); if (ret < 0)