Messages in this thread Patch in this message | | | From | Jiri Slaby <> | Subject | [PATCH 3.12 06/78] xen-netfront: Remove BUGs on paged skb data which crosses a page boundary | Date | Fri, 9 Jan 2015 11:31:15 +0100 |
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From: Seth Forshee <seth.forshee@canonical.com>
3.12-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit 8d609725d4357f499e2103e46011308b32f53513 ]
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") 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> Signed-off-by: Jiri Slaby <jslaby@suse.cz> --- 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 7c541dc1647e..fd3c1da14495 100644 --- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c @@ -468,9 +468,6 @@ static void xennet_make_frags(struct sk_buff *skb, struct net_device *dev, 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; @@ -478,8 +475,6 @@ static void xennet_make_frags(struct sk_buff *skb, struct net_device *dev, while (len > 0) { unsigned long bytes; - BUG_ON(offset >= PAGE_SIZE); - bytes = PAGE_SIZE - offset; if (bytes > len) bytes = len; -- 2.2.1
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