[PATCH 3.10 62/77] skbuff: skb_segment: orphan frags before copying

[Greg Kroah-Hartman]

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

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

From: "Michael S. Tsirkin" <mst@xxxxxxxxxx>

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@xxxxxxxxxx>
Acked-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
[bwh: Backported to 3.2.  As skb_segment() only supports page-frags *or* a
  frag list, there is no need for the additional frag_skb pointer or the
  preparatory renaming.]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Cc: Eddie Chapman <eddie@xxxxxxxx> # backported to 3.10
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2844,6 +2844,8 @@ struct sk_buff *skb_segment(struct sk_bu
 		skb_shinfo(nskb)->tx_flags = skb_shinfo(skb)->tx_flags & SKBTX_SHARED_FRAG;
 
 		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);


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