| From | Kamal Mostafa <> | Subject | [PATCH 025/105] xen-netback: don't disconnect frontend when seeing oversize packet | Date | Fri, 28 Jun 2013 11:50:47 -0700 |
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3.8.13.4 -stable review patch. If anyone has any objections, please let me know.
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From: Wei Liu <wei.liu2@citrix.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@citrix.com> Signed-off-by: Wei Liu <wei.liu2@citrix.com> Acked-by: Ian Campbell <ian.campbell@citrix.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/net/xen-netback/netback.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-)
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c index 2b50c67..b74bc4f 100644 --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -975,12 +975,22 @@ static int netbk_count_requests(struct xenvif *vif, 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; -- 1.8.1.2
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