Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Eric Dumazet <edumazet@google.com>,
        syzbot <syzkaller@googlegroups.com>,
        Florian Westphal <fw@strlen.de>,
        Pablo Neira Ayuso <pablo@netfilter.org>
Subject: [PATCH 4.14 036/159] netfilter: x_tables: avoid out-of-bounds reads in xt_request_find_{match|target}
Date:   Fri, 23 Feb 2018 19:25:44 +0100
Message-Id: <20180223170747.841183223@linuxfoundation.org>
In-Reply-To: <20180223170743.086611315@linuxfoundation.org>
References: <20180223170743.086611315@linuxfoundation.org>
User-Agent: quilt/0.65
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Dumazet <edumazet@google.com>

commit da17c73b6eb74aad3c3c0654394635675b623b3e upstream.

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 <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 net/netfilter/x_tables.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -209,6 +209,9 @@ xt_request_find_match(uint8_t nfproto, c
 {
 	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);
@@ -251,6 +254,9 @@ struct xt_target *xt_request_find_target
 {
 	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);