From: Jason Wang Date: Tue, 28 May 2013 18:32:11 +0000 (+0000) Subject: tuntap: forbid changing mq flag for persistent device X-Git-Tag: upstream/snapshot3+hdmi~4979^2~30 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=8e6d91ae0917bf934ed86411148f79d904728d51;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git tuntap: forbid changing mq flag for persistent device 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 Cc: Michael S. Tsirkin Signed-off-by: Jason Wang Signed-off-by: David S. Miller --- diff --git a/drivers/net/tun.c b/drivers/net/tun.c index f042b03..89776c5 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);