| From | Kamal Mostafa <> | Subject | [PATCH 079/105] tuntap: forbid changing mq flag for persistent device | Date | Fri, 28 Jun 2013 11:51:41 -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: Jason Wang <jasowang@redhat.com>
[ Upstream commit 8e6d91ae0917bf934ed86411148f79d904728d51 ]
We currently allow changing the mq flag (IFF_MULTI_QUEUE) for a persistent device. This will result a mismatch between the number the queues in netdev and tuntap. This is because we only allocate a 1q netdevice when IFF_MULTI_QUEUE was not specified, so when we set the IFF_MULTI_QUEUE and try to attach more queues later, netif_set_real_num_tx_queues() may fail which result a single queue netdevice with multiple sockets attached.
Solve this by disallowing changing the mq flag for persistent device.
Bug was introduced by commit edfb6a148ce62e5e19354a1dcd9a34e00815c2a1 (tuntap: reduce memory using of queues).
Reported-by: Sriram Narasimhan <sriram.narasimhan@hp.com> Cc: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/net/tun.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 522dc0a..2129cf90 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1585,6 +1585,10 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr) else return -EINVAL; + if (!!(ifr->ifr_flags & IFF_MULTI_QUEUE) != + !!(tun->flags & TUN_TAP_MQ)) + return -EINVAL; + if (tun_not_capable(tun)) return -EPERM; err = security_tun_dev_open(tun->security); -- 1.8.1.2
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