[PATCH 3.8 095/121] skbuff: skb_segment: orphan frags before copying

[Kamal Mostafa]

3.8.13.24 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: "Michael S. Tsirkin" <mst at redhat.com>

commit 1fd819ecb90cc9b822cd84d3056ddba315d3340f upstream.

skb_segment copies frags around, so we need
to copy them carefully to avoid accessing
user memory after reporting completion to userspace
through a callback.

skb_segment doesn't normally happen on datapath:
TSO needs to be disabled - so disabling zero copy
in this case does not look like a big deal.

Signed-off-by: Michael S. Tsirkin <mst at redhat.com>
Acked-by: Herbert Xu <herbert at gondor.apana.org.au>
Signed-off-by: David S. Miller <davem at davemloft.net>
(back ported from commit 1fd819ecb90cc9b822cd84d3056ddba315d3340f)
CVE-2014-0131
BugLink: http://bugs.launchpad.net/bugs/1298119
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 net/core/skbuff.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index f97fe58..1cee7e3 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2826,6 +2826,9 @@ struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features)
 						 skb_put(nskb, hsize), hsize);
 
 		while (pos < offset + len && i < nfrags) {
+			if (unlikely(skb_orphan_frags(skb, GFP_ATOMIC)))
+				goto err;
+
 			*frag = skb_shinfo(skb)->frags[i];
 			__skb_frag_ref(frag);
 			size = skb_frag_size(frag);
-- 
1.9.1