[PATCH 3.2 125/125] skbuff: skb_segment: orphan frags before copying

From: Ben Hutchings
Date: Tue Jul 08 2014 - 15:25:35 EST

3.2.61-rc1 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>
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2698,6 +2698,9 @@ 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];
size = skb_frag_size(frag);

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/