From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pablo Neira Ayuso Subject: [PATCH 10/12] netfilter: x_tables: avoid stack-out-of-bounds read in xt_copy_counters_from_user Date: Mon, 9 Oct 2017 18:25:44 +0200 Message-ID: <1507566346-32553-11-git-send-email-pablo@netfilter.org> References: <1507566346-32553-1-git-send-email-pablo@netfilter.org> Cc: davem@davemloft.net, netdev@vger.kernel.org To: netfilter-devel@vger.kernel.org Return-path: Received: from mail.us.es ([193.147.175.20]:57852 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755197AbdJIQ0H (ORCPT ); Mon, 9 Oct 2017 12:26:07 -0400 Received: from antivirus1-rhel7.int (unknown [192.168.2.11]) by mail.us.es (Postfix) with ESMTP id 9508BC0B3B for ; Mon, 9 Oct 2017 18:26:06 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 8661EDA38C for ; Mon, 9 Oct 2017 18:26:06 +0200 (CEST) In-Reply-To: <1507566346-32553-1-git-send-email-pablo@netfilter.org> Sender: netfilter-devel-owner@vger.kernel.org List-ID: From: Eric Dumazet syzkaller reports an out of bound read in strlcpy(), triggered by xt_copy_counters_from_user() Fix this by using memcpy(), then forcing a zero byte at the last position of the destination, as Florian did for the non COMPAT code. Fixes: d7591f0c41ce ("netfilter: x_tables: introduce and use xt_copy_counters_from_user") Signed-off-by: Eric Dumazet Cc: Willem de Bruijn Acked-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/x_tables.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c index c83a3b5e1c6c..d8571f414208 100644 --- a/net/netfilter/x_tables.c +++ b/net/netfilter/x_tables.c @@ -892,7 +892,7 @@ void *xt_copy_counters_from_user(const void __user *user, unsigned int len, if (copy_from_user(&compat_tmp, user, sizeof(compat_tmp)) != 0) return ERR_PTR(-EFAULT); - strlcpy(info->name, compat_tmp.name, sizeof(info->name)); + memcpy(info->name, compat_tmp.name, sizeof(info->name) - 1); info->num_counters = compat_tmp.num_counters; user += sizeof(compat_tmp); } else @@ -905,9 +905,9 @@ void *xt_copy_counters_from_user(const void __user *user, unsigned int len, if (copy_from_user(info, user, sizeof(*info)) != 0) return ERR_PTR(-EFAULT); - info->name[sizeof(info->name) - 1] = '\0'; user += sizeof(*info); } + info->name[sizeof(info->name) - 1] = '\0'; size = sizeof(struct xt_counters); size *= info->num_counters; -- 2.1.4