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Subject[PATCH 3.13 22/65] skbuff: skb_segment: orphan frags before copying
Date
3.13-stable review patch.  If anyone has any objections, please let me know.

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

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

[ Upstream commit 1fd819ecb90cc9b822cd84d3056ddba315d3340f ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/core/skbuff.c | 6 ++++++
1 file changed, 6 insertions(+)

--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2772,6 +2772,7 @@ struct sk_buff *skb_segment(struct sk_bu
skb_frag_t *frag = skb_shinfo(head_skb)->frags;
unsigned int mss = skb_shinfo(head_skb)->gso_size;
unsigned int doffset = head_skb->data - skb_mac_header(head_skb);
+ struct sk_buff *frag_skb = head_skb;
unsigned int offset = doffset;
unsigned int tnl_hlen = skb_tnl_header_len(head_skb);
unsigned int headroom;
@@ -2816,6 +2817,7 @@ struct sk_buff *skb_segment(struct sk_bu
i = 0;
nfrags = skb_shinfo(list_skb)->nr_frags;
frag = skb_shinfo(list_skb)->frags;
+ frag_skb = list_skb;
pos += skb_headlen(list_skb);

while (pos < offset + len) {
@@ -2903,6 +2905,7 @@ struct sk_buff *skb_segment(struct sk_bu
i = 0;
nfrags = skb_shinfo(list_skb)->nr_frags;
frag = skb_shinfo(list_skb)->frags;
+ frag_skb = list_skb;

BUG_ON(!nfrags);

@@ -2917,6 +2920,9 @@ struct sk_buff *skb_segment(struct sk_bu
goto err;
}

+ if (unlikely(skb_orphan_frags(frag_skb, GFP_ATOMIC)))
+ goto err;
+
*nskb_frag = *frag;
__skb_frag_ref(nskb_frag);
size = skb_frag_size(nskb_frag);



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