This is a note to let you know that I've just added the patch titled

gso: validate gso_type in GSO handlers

to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: gso-validate-gso_type-in-gso-handlers.patch and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Sun Jan 28 17:37:09 CET 2018

From: Willem de Bruijn willemb@google.com Date: Fri, 19 Jan 2018 09:29:18 -0500 Subject: gso: validate gso_type in GSO handlers

From: Willem de Bruijn willemb@google.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@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 --- 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;

Patches currently in stable-queue which might be from willemb@google.com are

queue-4.9/gso-validate-gso_type-in-gso-handlers.patch queue-4.9/flow_dissector-properly-cap-thoff-field.patch queue-4.9/net-qdisc_pkt_len_init-should-be-more-robust.patch