Patch "sch_dsmark: fix invalid skb_cow() usage" has been added to the 4.9-stable tree

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 4.9-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-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Eric Dumazet <[email protected]>
Date: Fri, 17 Mar 2017 08:05:28 -0700
Subject: sch_dsmark: fix invalid skb_cow() usage

From: Eric Dumazet <[email protected]>

[ 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.

---
 net/sched/sch_dsmark.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

@@ -200,9 +200,13 @@ 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))

@@ -210,7 +214,9 @@ 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 [email protected] are

queue-4.9/sch_dsmark-fix-invalid-skb_cow-usage.patch queue-4.9/inet-frag-release-spinlock-before-calling-icmp_send.patch queue-4.9/net-do-not-allow-negative-values-for-busy_read-and-busy_poll-sysctl-interfaces.patch