linux-kernel - [PATCH 4.9 52/66] gso: validate gso

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Message-Id: <20180129123842.630859423@linuxfoundation.org>
Date:   Mon, 29 Jan 2018 13:57:16 +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,
        syzbot+fee64147a25aecd48055@...kaller.appspotmail.com,
        Willem de Bruijn <willemb@...gle.com>,
        Jason Wang <jasowang@...hat.com>,
        Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.9 52/66] gso: validate gso_type in GSO handlers

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

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

From: Willem de Bruijn <willemb@...gle.com>


[ Upstream commit 121d57af308d0cf943f08f4738d24d3966c38cd9 ]

Validate gso_type during segmentation as SKB_GSO_DODGY sources
may pass packets where the gso_type does not match the contents.

Syzkaller was able to enter the SCTP gso handler with a packet of
gso_type SKB_GSO_TCPV4.

On entry of transport layer gso handlers, verify that the gso_type
matches the transport protocol.

Fixes: 90017accff61 ("sctp: Add GSO support")
Link: http://lkml.kernel.org/r/<001a1137452496ffc305617e5fe0@...gle.com>
Reported-by: syzbot+fee64147a25aecd48055@...kaller.appspotmail.com
Signed-off-by: Willem de Bruijn <willemb@...gle.com>
Acked-by: Jason Wang <jasowang@...hat.com>
Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/ipv4/tcp_offload.c   |    3 +++
 net/ipv4/udp_offload.c   |    3 +++
 net/ipv6/tcpv6_offload.c |    3 +++
 net/ipv6/udp_offload.c   |    3 +++
 net/sctp/offload.c       |    3 +++
 5 files changed, 15 insertions(+)

--- a/net/ipv4/tcp_offload.c
+++ b/net/ipv4/tcp_offload.c
@@ -32,6 +32,9 @@ static void tcp_gso_tstamp(struct sk_buf
 static struct sk_buff *tcp4_gso_segment(struct sk_buff *skb,
 					netdev_features_t features)
 {
+	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4))
+		return ERR_PTR(-EINVAL);
+
 	if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
 		return ERR_PTR(-EINVAL);
 
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -205,6 +205,9 @@ static struct sk_buff *udp4_ufo_fragment
 		goto out;
 	}
 
+	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP))
+		goto out;
+
 	if (!pskb_may_pull(skb, sizeof(struct udphdr)))
 		goto out;
 
--- a/net/ipv6/tcpv6_offload.c
+++ b/net/ipv6/tcpv6_offload.c
@@ -46,6 +46,9 @@ static struct sk_buff *tcp6_gso_segment(
 {
 	struct tcphdr *th;
 
+	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6))
+		return ERR_PTR(-EINVAL);
+
 	if (!pskb_may_pull(skb, sizeof(*th)))
 		return ERR_PTR(-EINVAL);
 
--- a/net/ipv6/udp_offload.c
+++ b/net/ipv6/udp_offload.c
@@ -55,6 +55,9 @@ static struct sk_buff *udp6_ufo_fragment
 		const struct ipv6hdr *ipv6h;
 		struct udphdr *uh;
 
+		if (!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP))
+			goto out;
+
 		if (!pskb_may_pull(skb, sizeof(struct udphdr)))
 			goto out;
 
--- a/net/sctp/offload.c
+++ b/net/sctp/offload.c
@@ -44,6 +44,9 @@ static struct sk_buff *sctp_gso_segment(
 	struct sk_buff *segs = ERR_PTR(-EINVAL);
 	struct sctphdr *sh;
 
+	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_SCTP))
+		goto out;
+
 	sh = sctp_hdr(skb);
 	if (!pskb_may_pull(skb, sizeof(*sh)))
 		goto out;