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xen-netfront: Remove BUGs on paged skb data which crosses a page boundary 

These BUGs can be erroneously triggered by frags which refer to
tail pages within a compound page. The data in these pages may
overrun the hardware page while still being contained within the
compound page, but since compound_order() evaluates to 0 for tail
pages the assertion fails. The code already iterates through
subsequent pages correctly in this scenario, so the BUGs are
unnecessary and can be removed.

Fixes: f36c374782 ("xen/netfront: handle compound page fragments on transmit")
Cc: <stable@vger.kernel.org> # 3.7+
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
hifive-unleashed-5.1
Seth Forshee 2014-11-25 20:28:24 -06:00 committed by David S. Miller
parent 7fa2955ff7
commit 8d609725d4
1 changed files with 0 additions and 5 deletions
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5
drivers/net/xen-netfront.c
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@ -496,9 +496,6 @@ static void xennet_make_frags(struct sk_buff *skb, struct netfront_queue *queue,
len = skb_frag_size(frag);
offset = frag->page_offset;
/* Data must not cross a page boundary. */
BUG_ON(len + offset > PAGE_SIZE<<compound_order(page));
/* Skip unused frames from start of page */
page += offset >> PAGE_SHIFT;
offset &= ~PAGE_MASK;
@ -506,8 +503,6 @@ static void xennet_make_frags(struct sk_buff *skb, struct netfront_queue *queue,
while (len > 0) {
unsigned long bytes;
BUG_ON(offset >= PAGE_SIZE);
bytes = PAGE_SIZE - offset;
if (bytes > len)
bytes = len;