Patch "net: qdisc_pkt_len_init() should be more robust" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

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 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-qdisc_pkt_len_init-should-be-more-robust.patch
and it can be found in the queue-4.4 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 10:14:57 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
@@ -2889,10 +2889,21 @@ 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-4.4/ipv6-fix-udpv6-sendmsg-crash-caused-by-too-small-mtu.patch
queue-4.4/flow_dissector-properly-cap-thoff-field.patch
queue-4.4/ipv6-ip6_make_skb-needs-to-clear-cork.base.dst.patch
queue-4.4/dccp-don-t-restart-ccid2_hc_tx_rto_expire-if-sk-in-closed-state.patch
queue-4.4/netfilter-restart-search-if-moved-to-other-chain.patch
queue-4.4/net-qdisc_pkt_len_init-should-be-more-robust.patch