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>
---
For branches older than 3.6, commit a353e0ce0fd4 ('skbuff: add an api to
orphan frags') is needed before this. This is untested and I would
appreciate a review.
Ben.
---
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2699,6 +2699,9 @@ struct sk_buff *skb_segment(struct sk_bu
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);
--
Ben Hutchings
I haven't lost my mind; it's backed up on tape somewhere.
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