From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: [PATCH v2 net] netfilter: x_tables: avoid out-of-bounds reads in xt_request_find_{match|target} Date: Wed, 24 Jan 2018 17:16:09 -0800 Message-ID: <1516842969.3715.41.camel@gmail.com> References: <1516834188.3715.35.camel@gmail.com> <20180124231952.GC14192@breakpoint.cc> <20180124235056.ahubcyqostttvtbx@salvia> <20180125001336.ilboagwlcpck54ip@salvia> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Cc: netdev , netfilter-devel@vger.kernel.org To: Pablo Neira Ayuso , Florian Westphal Return-path: Received: from mail-pf0-f196.google.com ([209.85.192.196]:34564 "EHLO mail-pf0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751109AbeAYBQL (ORCPT ); Wed, 24 Jan 2018 20:16:11 -0500 In-Reply-To: <20180125001336.ilboagwlcpck54ip@salvia> Sender: netdev-owner@vger.kernel.org List-ID: From: Eric Dumazet It looks like syzbot found its way into netfilter territory. Issue here is that @name comes from user space and might not be null terminated. Out-of-bound reads happen, KASAN is not happy. v2 added similar fix for xt_request_find_target(), as Florian advised. Signed-off-by: Eric Dumazet Reported-by: syzbot --- No Fixes: tag, bug seems to be a day-0 one.  net/netfilter/x_tables.c |    6 ++++++  1 file changed, 6 insertions(+) diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c index 55802e97f906d1987ed78b4296584deb38e5f876..ecffc51ce83b07c063a0db67cdb33d9bf48a75ac 100644 --- a/net/netfilter/x_tables.c +++ b/net/netfilter/x_tables.c @@ -210,6 +210,9 @@ xt_request_find_match(uint8_t nfproto, const char *name, uint8_t revision) { struct xt_match *match; + if (strnlen(name, XT_EXTENSION_MAXNAMELEN) == XT_EXTENSION_MAXNAMELEN) + return ERR_PTR(-EINVAL); + match = xt_find_match(nfproto, name, revision); if (IS_ERR(match)) { request_module("%st_%s", xt_prefix[nfproto], name); @@ -252,6 +255,9 @@ struct xt_target *xt_request_find_target(u8 af, const char *name, u8 revision) { struct xt_target *target; + if (strnlen(name, XT_EXTENSION_MAXNAMELEN) == XT_EXTENSION_MAXNAMELEN) + return ERR_PTR(-EINVAL); + target = xt_find_target(af, name, revision); if (IS_ERR(target)) { request_module("%st_%s", xt_prefix[af], name);