Commit 0e1d6eca authored Oct 02, 2018 by Eric Dumazet Committed by David S. Miller Oct 02, 2018

rtnl: limit IFLA_NUM_TX_QUEUES and IFLA_NUM_RX_QUEUES to 4096



We have an impressive number of syzkaller bugs that are linked
to the fact that syzbot was able to create a networking device
with millions of TX (or RX) queues.

Let's limit the number of RX/TX queues to 4096, this really should
cover all known cases.

A separate patch will add various cond_resched() in the loops
handling sysfs entries at device creation and dismantle.

Tested:

lpaa6:~# ip link add gre-4097 numtxqueues 4097 numrxqueues 4097 type ip6gretap
RTNETLINK answers: Invalid argument

lpaa6:~# time ip link add gre-4096 numtxqueues 4096 numrxqueues 4096 type ip6gretap

real	0m0.180s
user	0m0.000s
sys	0m0.107s

Fixes: 76ff5cc9 ("rtnl: allow to specify number of rx and tx queues on device creation")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 0f3b914c

net/core/rtnetlink.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -2835,6 +2835,12 @@ struct net_device rtnl_create_link(struct net net,
		else if (ops->get_num_rx_queues)
		num_rx_queues = ops->get_num_rx_queues();

		if (num_tx_queues < 1 \|\| num_tx_queues > 4096)
		return ERR_PTR(-EINVAL);

		if (num_rx_queues < 1 \|\| num_rx_queues > 4096)
		return ERR_PTR(-EINVAL);

		dev = alloc_netdev_mqs(ops->priv_size, ifname, name_assign_type,
		ops->setup, num_tx_queues, num_rx_queues);
		if (!dev)

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