linux-kernel - [PATCH 4.4 09/25] ip: fix IP

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: <20170224082129.478016443@linuxfoundation.org>
Date:   Fri, 24 Feb 2017 09:25:21 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Andrey Konovalov <andreyknvl@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Eric Dumazet <edumazet@...gle.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.4 09/25] ip: fix IP_CHECKSUM handling

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

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

From: Paolo Abeni <pabeni@...hat.com>


[ Upstream commit ca4ef4574f1ee5252e2cd365f8f5d5bafd048f32 ]

The skbs processed by ip_cmsg_recv() are not guaranteed to
be linear e.g. when sending UDP packets over loopback with
MSGMORE.
Using csum_partial() on [potentially] the whole skb len
is dangerous; instead be on the safe side and use skb_checksum().

Thanks to syzkaller team to detect the issue and provide the
reproducer.

v1 -> v2:
 - move the variable declaration in a tighter scope

Fixes: ad6f939ab193 ("ip: Add offset parameter to ip_cmsg_recv")
Reported-by: Andrey Konovalov <andreyknvl@...gle.com>
Signed-off-by: Paolo Abeni <pabeni@...hat.com>
Acked-by: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/ipv4/ip_sockglue.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -105,10 +105,10 @@ static void ip_cmsg_recv_checksum(struct
 	if (skb->ip_summed != CHECKSUM_COMPLETE)
 		return;
 
-	if (offset != 0)
-		csum = csum_sub(csum,
-				csum_partial(skb->data + tlen,
-					     offset, 0));
+	if (offset != 0) {
+		int tend_off = skb_transport_offset(skb) + tlen;
+		csum = csum_sub(csum, skb_checksum(skb, tend_off, offset, 0));
+	}
 
 	put_cmsg(msg, SOL_IP, IP_CHECKSUM, sizeof(__wsum), &csum);
 }