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

net: qdisc_pkt_len_init() should be more robust

to the 3.18-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: net-qdisc_pkt_len_init-should-be-more-robust.patch and it can be found in the queue-3.18 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 Mon Jan 29 11:15:06 CET 2018

From: Eric Dumazet edumazet@google.com Date: Thu, 18 Jan 2018 19:59:19 -0800 Subject: net: qdisc_pkt_len_init() should be more robust

From: Eric Dumazet edumazet@google.com

[ Upstream commit 7c68d1a6b4db9012790af7ac0f0fdc0d2083422a ]

Without proper validation of DODGY packets, we might very well feed qdisc_pkt_len_init() with invalid GSO packets.

tcp_hdrlen() might access out-of-bound data, so let's use skb_header_pointer() and proper checks.

Whole story is described in commit d0c081b49137 ("flow_dissector: properly cap thoff field")

We have the goal of validating DODGY packets earlier in the stack, so we might very well revert this fix in the future.

Signed-off-by: Eric Dumazet edumazet@google.com Cc: Willem de Bruijn willemb@google.com Cc: Jason Wang jasowang@redhat.com Reported-by: syzbot+9da69ebac7dddd804552@syzkaller.appspotmail.com Acked-by: Jason Wang jasowang@redhat.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/core/dev.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-)

--- a/net/core/dev.c +++ b/net/core/dev.c @@ -2772,10 +2772,21 @@ static void qdisc_pkt_len_init(struct sk hdr_len = skb_transport_header(skb) - skb_mac_header(skb);

/* + transport layer */ - if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))) - hdr_len += tcp_hdrlen(skb); - else - hdr_len += sizeof(struct udphdr); + if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))) { + const struct tcphdr *th; + struct tcphdr _tcphdr; + + th = skb_header_pointer(skb, skb_transport_offset(skb), + sizeof(_tcphdr), &_tcphdr); + if (likely(th)) + hdr_len += __tcp_hdrlen(th); + } else { + struct udphdr _udphdr; + + if (skb_header_pointer(skb, skb_transport_offset(skb), + sizeof(_udphdr), &_udphdr)) + hdr_len += sizeof(struct udphdr); + }

if (shinfo->gso_type & SKB_GSO_DODGY) gso_segs = DIV_ROUND_UP(skb->len - hdr_len,

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

queue-3.18/ipv6-fix-udpv6-sendmsg-crash-caused-by-too-small-mtu.patch queue-3.18/dccp-don-t-restart-ccid2_hc_tx_rto_expire-if-sk-in-closed-state.patch queue-3.18/netfilter-restart-search-if-moved-to-other-chain.patch queue-3.18/net-qdisc_pkt_len_init-should-be-more-robust.patch