Patch "vlan: pull on __vlan_insert_tag error path and fix csum correction" has been added to the 4.4-stable tree

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

vlan: pull on __vlan_insert_tag error path and fix csum correction

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:
vlan-pull-on-__vlan_insert_tag-error-path-and-fix-csum-correction.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 <[email protected]> know about it.

From: Daniel Borkmann <[email protected]>
Date: Sat, 16 Apr 2016 02:27:58 +0200
Subject: vlan: pull on __vlan_insert_tag error path and fix csum correction

From: Daniel Borkmann <[email protected]>

[ Upstream commit 9241e2df4fbc648a92ea0752918e05c26255649e ]

When __vlan_insert_tag() fails from skb_vlan_push() path due to the skb_cow_head(), we need to undo the __skb_push() in the error path as well that was done earlier to move skb->data pointer to mac header.

Moreover, I noticed that when in the non-error path the __skb_pull() is done and the original offset to mac header was non-zero, we fixup from a wrong skb->data offset in the checksum complete processing.

So the skb_postpush_rcsum() really needs to be done before __skb_pull() where skb->data still points to the mac header start and thus operates under the same conditions as in __vlan_insert_tag().

---
 net/core/skbuff.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

@@ -4427,13 +4427,16 @@ int skb_vlan_push(struct sk_buff *skb, _
 		__skb_push(skb, offset);
 		err = __vlan_insert_tag(skb, skb->vlan_proto,
 					skb_vlan_tag_get(skb));
-		if (err)
+		if (err) {
+			__skb_pull(skb, offset);
 			return err;
+		}
+
 		skb->protocol = skb->vlan_proto;
 		skb->mac_len += VLAN_HLEN;
-		__skb_pull(skb, offset);
 
 		skb_postpush_rcsum(skb, skb->data + (2 * ETH_ALEN), VLAN_HLEN);
+		__skb_pull(skb, offset);
 	}
 	__vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
 	return 0;

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/bpf-fix-double-fdput-in-replace_map_fd_with_map_ptr.patch queue-4.4/vlan-pull-on-__vlan_insert_tag-error-path-and-fix-csum-correction.patch queue-4.4/bpf-fix-refcnt-overflow.patch queue-4.4/bpf-verifier-reject-invalid-ld_abs-bpf_dw-instruction.patch queue-4.4/net-use-skb_postpush_rcsum-instead-of-own-implementations.patch queue-4.4/bpf-fix-check_map_func_compatibility-logic.patch