From: Willem de Bruijn <willemb@google.com>
Date: Fri, 19 Jan 2018 14:29:18 +0000 (-0500)
Subject: gso: validate gso_type in GSO handlers
X-Git-Tag: C0P2-H0.0--20200415~5557
X-Git-Url: https://git.somdevices.com/?a=commitdiff_plain;h=3110e2134c9718a1f3c091873769d1d9b621bb87;p=linux.git

gso: validate gso_type in GSO handlers


[ 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@google.com>
Reported-by: syzbot+fee64147a25aecd48055@syzkaller.appspotmail.com
Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c
index bc68da38ea86..366b1becff9d 100644
--- a/net/ipv4/tcp_offload.c
+++ b/net/ipv4/tcp_offload.c
@@ -32,6 +32,9 @@ static void tcp_gso_tstamp(struct sk_buff *skb, unsigned int ts_seq,
 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);
 
diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index 6401574cd638..f4f616eaaeb8 100644
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -205,6 +205,9 @@ static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
 		goto out;
 	}
 
+	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP))
+		goto out;
+
 	if (!pskb_may_pull(skb, sizeof(struct udphdr)))
 		goto out;
 
diff --git a/net/ipv6/tcpv6_offload.c b/net/ipv6/tcpv6_offload.c
index d883c9204c01..278e49cd67d4 100644
--- a/net/ipv6/tcpv6_offload.c
+++ b/net/ipv6/tcpv6_offload.c
@@ -46,6 +46,9 @@ static struct sk_buff *tcp6_gso_segment(struct sk_buff *skb,
 {
 	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);
 
diff --git a/net/ipv6/udp_offload.c b/net/ipv6/udp_offload.c
index e7d378c032cb..2bd2087bd105 100644
--- a/net/ipv6/udp_offload.c
+++ b/net/ipv6/udp_offload.c
@@ -55,6 +55,9 @@ static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
 		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;
 
diff --git a/net/sctp/offload.c b/net/sctp/offload.c
index 4f5a2b580aa5..6300f28c9588 100644
--- a/net/sctp/offload.c
+++ b/net/sctp/offload.c
@@ -44,6 +44,9 @@ static struct sk_buff *sctp_gso_segment(struct sk_buff *skb,
 	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;