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

Greg Kroah-Hartman
2014-06-28T19:04:06Z

From: "Michael S. Tsirkin" <mst@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@redhat.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
[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@decadent.org.uk>
Cc: Eddie Chapman <eddie@ehuk.net> # backported to 3.10
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
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);