Patch "sch_dsmark: fix invalid skb_cow() usage" has been added to the 4.4-stable tree

Patch "sch_dsmark: fix invalid skb_cow() usage" has been added to the 4.4-stable tree

[gregkh]

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

    sch_dsmark: fix invalid skb_cow() usage

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:
     sch_dsmark-fix-invalid-skb_cow-usage.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 Thu Dec 21 10:35:49 CET 2017
From: Eric Dumazet <edumazet@google.com>
Date: Fri, 17 Mar 2017 08:05:28 -0700
Subject: sch_dsmark: fix invalid skb_cow() usage

From: Eric Dumazet <edumazet@google.com>


[ Upstream commit aea92fb2e09e29653b023d4254ac9fbf94221538 ]

skb_cow(skb, sizeof(ip header)) is not very helpful in this context.

First we need to use pskb_may_pull() to make sure the ip header
is in skb linear part, then use skb_try_make_writable() to
address clones issues.

Fixes: 4c30719f4f55 ("[PKT_SCHED] dsmark: handle cloned and non-linear skb's")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/sched/sch_dsmark.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

--- a/net/sched/sch_dsmark.c
+++ b/net/sched/sch_dsmark.c
@@ -199,9 +199,13 @@ static int dsmark_enqueue(struct sk_buff
 	pr_debug("%s(skb %p,sch %p,[qdisc %p])\n", __func__, skb, sch, p);
 
 	if (p->set_tc_index) {
+		int wlen = skb_network_offset(skb);
+
 		switch (tc_skb_protocol(skb)) {
 		case htons(ETH_P_IP):
-			if (skb_cow_head(skb, sizeof(struct iphdr)))
+			wlen += sizeof(struct iphdr);
+			if (!pskb_may_pull(skb, wlen) ||
+			    skb_try_make_writable(skb, wlen))
 				goto drop;
 
 			skb->tc_index = ipv4_get_dsfield(ip_hdr(skb))
@@ -209,7 +213,9 @@ static int dsmark_enqueue(struct sk_buff
 			break;
 
 		case htons(ETH_P_IPV6):
-			if (skb_cow_head(skb, sizeof(struct ipv6hdr)))
+			wlen += sizeof(struct ipv6hdr);
+			if (!pskb_may_pull(skb, wlen) ||
+			    skb_try_make_writable(skb, wlen))
 				goto drop;
 
 			skb->tc_index = ipv6_get_dsfield(ipv6_hdr(skb))


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

queue-4.4/sch_dsmark-fix-invalid-skb_cow-usage.patch
queue-4.4/inet-frag-release-spinlock-before-calling-icmp_send.patch
queue-4.4/net-do-not-allow-negative-values-for-busy_read-and-busy_poll-sysctl-interfaces.patch