netdev - [PATCH 01/15] netfilter: xt_CT: Reject the non-null terminated string from user space

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20180611092233.3219-2-pablo@netfilter.org>
Date:   Mon, 11 Jun 2018 11:22:19 +0200
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     netfilter-devel@...r.kernel.org
Cc:     davem@...emloft.net, netdev@...r.kernel.org
Subject: [PATCH 01/15] netfilter: xt_CT: Reject the non-null terminated string from user space

From: Gao Feng <gfree.wind@....163.com>

The helper and timeout strings are from user-space, we need to make
sure they are null terminated. If not, evil user could make kernel
read the unexpected memory, even print it when fail to find by the
following codes.

pr_info_ratelimited("No such helper \"%s\"\n", helper_name);

Signed-off-by: Gao Feng <gfree.wind@....163.com>
Acked-by: Florian Westphal <fw@...len.de>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 net/netfilter/xt_CT.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/net/netfilter/xt_CT.c b/net/netfilter/xt_CT.c
index 8790190c6feb..03b9a50ec93b 100644
--- a/net/netfilter/xt_CT.c
+++ b/net/netfilter/xt_CT.c
@@ -245,12 +245,22 @@ static int xt_ct_tg_check(const struct xt_tgchk_param *par,
 	}
 
 	if (info->helper[0]) {
+		if (strnlen(info->helper, sizeof(info->helper)) == sizeof(info->helper)) {
+			ret = -ENAMETOOLONG;
+			goto err3;
+		}
+
 		ret = xt_ct_set_helper(ct, info->helper, par);
 		if (ret < 0)
 			goto err3;
 	}
 
 	if (info->timeout[0]) {
+		if (strnlen(info->timeout, sizeof(info->timeout)) == sizeof(info->timeout)) {
+			ret = -ENAMETOOLONG;
+			goto err4;
+		}
+
 		ret = xt_ct_set_timeout(ct, par, info->timeout);
 		if (ret < 0)
 			goto err4;
-- 
2.11.0