From 92bb73ea2c434618a68a58a2f3a5c3fd0b660d18 Mon Sep 17 00:00:00 2001 From: Jason Wang Date: Wed, 5 Jun 2013 16:44:57 +0800 Subject: tuntap: fix a possible race between queue selection and changing queues Complier may generate codes that re-read the tun->numqueues during tun_select_queue(). This may be a race if vlan->numqueues were changed in the same time and can lead unexpected result (e.g. very huge value). We need prevent the compiler from generating such codes by adding an ACCESS_ONCE() to make sure tun->numqueues were only read once. Bug were introduced by commit c8d68e6be1c3b242f1c598595830890b65cea64a (tuntap: multiqueue support). Reported-by: Michael S. Tsirkin Cc: Michael S. Tsirkin Signed-off-by: Jason Wang Acked-by: Michael S. Tsirkin Signed-off-by: David S. Miller --- drivers/net/tun.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/net/tun.c') diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 89776c5..b1cbfbc 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -352,7 +352,7 @@ static u16 tun_select_queue(struct net_device *dev, struct sk_buff *skb) u32 numqueues = 0; rcu_read_lock(); - numqueues = tun->numqueues; + numqueues = ACCESS_ONCE(tun->numqueues); txq = skb_get_rxhash(skb); if (txq) { -- cgit v1.1 From 19a6afb23e5d323e1245baa4e62755492b2f1200 Mon Sep 17 00:00:00 2001 From: Jason Wang Date: Sat, 8 Jun 2013 14:17:41 +0800 Subject: tuntap: set SOCK_ZEROCOPY flag during open Commit 54f968d6efdbf7dec36faa44fc11f01b0e4d1990 (tuntap: move socket to tun_file) forgets to set SOCK_ZEROCOPY flag, which will prevent vhost_net from doing zercopy w/ tap. This patch fixes this by setting it during file open. Cc: Michael S. Tsirkin Signed-off-by: Jason Wang Acked-by: Michael S. Tsirkin Signed-off-by: David S. Miller --- drivers/net/tun.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'drivers/net/tun.c') diff --git a/drivers/net/tun.c b/drivers/net/tun.c index b1cbfbc..bfa9bb4 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -2159,6 +2159,8 @@ static int tun_chr_open(struct inode *inode, struct file * file) set_bit(SOCK_EXTERNALLY_ALLOCATED, &tfile->socket.flags); INIT_LIST_HEAD(&tfile->next); + sock_set_flag(&tfile->sk, SOCK_ZEROCOPY); + return 0; } -- cgit v1.1