Commit 73078f5b authored Jun 07, 2018 by Florian Westphal Committed by Greg Kroah-Hartman Jul 22, 2018

netfilter: x_tables: initialise match/target check parameter struct



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>

parent c5f2c5be

net/bridge/netfilter/ebtables.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -699,6 +699,8 @@ ebt_check_entry(struct ebt_entry e, struct net net,
		}
		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;

net/ipv4/netfilter/ip_tables.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -651,6 +651,7 @@ find_check_entry(struct ipt_entry e, struct net net, const char *name,
		struct xt_entry_match *ematch;

		j = 0;
		memset(&mtpar, 0, sizeof(mtpar));
		mtpar.net = net;
		mtpar.table = name;
		mtpar.entryinfo = &e->ip;

net/ipv6/netfilter/ip6_tables.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -662,6 +662,7 @@ find_check_entry(struct ip6t_entry e, struct net net, const char *name,
		struct xt_entry_match *ematch;

		j = 0;
		memset(&mtpar, 0, sizeof(mtpar));
		mtpar.net = net;
		mtpar.table = name;
		mtpar.entryinfo = &e->ipv6;