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Date: Fri, 7 Mar 2014 17:08:09 -0800 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, David Vrabel <david.vrabel@...rix.com>, Wei Liu <wei.liu2@...rix.com>, Ian Campbell <ian.campbell@...rix.com>, "David S. Miller" <davem@...emloft.net>, Ben Hutchings <ben@...adent.org.uk>, Yijing Wang <wangyijing@...wei.com> Subject: [PATCH 3.4 73/99] xen-netback: dont disconnect frontend when seeing oversize packet 3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Wei Liu <wei.liu2@...rix.com> commit 03393fd5cc2b6cdeec32b704ecba64dbb0feae3c upstream. Some frontend drivers are sending packets > 64 KiB in length. This length overflows the length field in the first slot making the following slots have an invalid length. Turn this error back into a non-fatal error by dropping the packet. To avoid having the following slots having fatal errors, consume all slots in the packet. This does not reopen the security hole in XSA-39 as if the packet as an invalid number of slots it will still hit fatal error case. Signed-off-by: David Vrabel <david.vrabel@...rix.com> Signed-off-by: Wei Liu <wei.liu2@...rix.com> Acked-by: Ian Campbell <ian.campbell@...rix.com> Signed-off-by: David S. Miller <davem@...emloft.net> Signed-off-by: Ben Hutchings <ben@...adent.org.uk> Cc: Yijing Wang <wangyijing@...wei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> --- drivers/net/xen-netback/netback.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -947,12 +947,22 @@ static int netbk_count_requests(struct x memcpy(txp, RING_GET_REQUEST(&vif->tx, cons + slots), sizeof(*txp)); - if (txp->size > first->size) { - netdev_err(vif->dev, - "Invalid tx request, slot size %u > remaining size %u\n", - txp->size, first->size); - netbk_fatal_tx_err(vif); - return -EIO; + + /* If the guest submitted a frame >= 64 KiB then + * first->size overflowed and following slots will + * appear to be larger than the frame. + * + * This cannot be fatal error as there are buggy + * frontends that do this. + * + * Consume all slots and drop the packet. + */ + if (!drop_err && txp->size > first->size) { + if (net_ratelimit()) + netdev_dbg(vif->dev, + "Invalid tx request, slot size %u > remaining size %u\n", + txp->size, first->size); + drop_err = -EIO; } first->size -= txp->size; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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