[3.16.y-ckt stable] Patch "xen-netfront: Remove BUGs on paged skb data which crosses a page boundary" has been added to staging queue
Luis Henriques
luis.henriques at canonical.com
Wed Dec 10 17:26:53 UTC 2014
This is a note to let you know that I have just added a patch titled
xen-netfront: Remove BUGs on paged skb data which crosses a page boundary
to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree
which can be found at:
http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue
This patch is scheduled to be released in version 3.16.7-ckt3.
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Luis
------
>From 5585fbc5bbf13446ffb8d3874df9f007253cde3d Mon Sep 17 00:00:00 2001
From: Seth Forshee <seth.forshee at canonical.com>
Date: Tue, 25 Nov 2014 20:28:24 -0600
Subject: xen-netfront: Remove BUGs on paged skb data which crosses a page
boundary
commit 8d609725d4357f499e2103e46011308b32f53513 upstream.
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: f36c374782e4 ("xen/netfront: handle compound page fragments on transmit")
Signed-off-by: Seth Forshee <seth.forshee at canonical.com>
Reviewed-by: David Vrabel <david.vrabel at citrix.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
drivers/net/xen-netfront.c | 5 -----
1 file changed, 5 deletions(-)
diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index 23359aeb1ba0..3e0019503440 100644
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -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;
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