netfilter: x_tables: initialise match/target check parameter struct
authorFlorian Westphal <fw@strlen.de>
Thu, 7 Jun 2018 19:34:43 +0000 (21:34 +0200)
committerPablo Neira Ayuso <pablo@netfilter.org>
Fri, 8 Jun 2018 10:40:56 +0000 (12:40 +0200)
commitc568503ef02030f169c9e19204def610a3510918
treeb0ba7bf264106a74e9efe06c39cf401a810ffad4
parent64e6dd1fb2f1ed799f317dc34aa6e251c64f4981
netfilter: x_tables: initialise match/target check parameter struct

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>
net/bridge/netfilter/ebtables.c
net/ipv4/netfilter/ip_tables.c
net/ipv6/netfilter/ip6_tables.c