4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Florian Westphal fw@strlen.de
commit c568503ef02030f169c9e19204def610a3510918 upstream.
syzbot reports following splat:
BUG: KMSAN: uninit-value in ebt_stp_mt_check+0x24b/0x450 net/bridge/netfilter/ebt_stp.c:162 ebt_stp_mt_check+0x24b/0x450 net/bridge/netfilter/ebt_stp.c:162 xt_check_match+0x1438/0x1650 net/netfilter/x_tables.c:506 ebt_check_match net/bridge/netfilter/ebtables.c:372 [inline] ebt_check_entry net/bridge/netfilter/ebtables.c:702 [inline]
The uninitialised access is xt_mtchk_param->nft_compat
... which should be set to 0. Fix it by zeroing the struct beforehand, same for tgchk.
ip(6)tables targetinfo uses c99-style initialiser, so no change needed there.
Reported-by: syzbot+da4494182233c23a5fcf@syzkaller.appspotmail.com Fixes: 55917a21d0cc0 ("netfilter: x_tables: add context to know if extension runs from nft_compat") 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 | 2 ++ net/ipv4/netfilter/ip_tables.c | 1 + net/ipv6/netfilter/ip6_tables.c | 1 + 3 files changed, 4 insertions(+)
--- a/net/bridge/netfilter/ebtables.c +++ b/net/bridge/netfilter/ebtables.c @@ -704,6 +704,8 @@ ebt_check_entry(struct ebt_entry *e, str } i = 0;
+ memset(&mtpar, 0, sizeof(mtpar)); + memset(&tgpar, 0, sizeof(tgpar)); mtpar.net = tgpar.net = net; mtpar.table = tgpar.table = name; mtpar.entryinfo = tgpar.entryinfo = e; --- a/net/ipv4/netfilter/ip_tables.c +++ b/net/ipv4/netfilter/ip_tables.c @@ -554,6 +554,7 @@ find_check_entry(struct ipt_entry *e, st return -ENOMEM;
j = 0; + memset(&mtpar, 0, sizeof(mtpar)); mtpar.net = net; mtpar.table = name; mtpar.entryinfo = &e->ip; --- a/net/ipv6/netfilter/ip6_tables.c +++ b/net/ipv6/netfilter/ip6_tables.c @@ -584,6 +584,7 @@ find_check_entry(struct ip6t_entry *e, s return -ENOMEM;
j = 0; + memset(&mtpar, 0, sizeof(mtpar)); mtpar.net = net; mtpar.table = name; mtpar.entryinfo = &e->ipv6;