Commit dcea9310 authored by Eric Dumazet's avatar Eric Dumazet Committed by Greg Kroah-Hartman

rtnl: limit IFLA_NUM_TX_QUEUES and IFLA_NUM_RX_QUEUES to 4096

[ Upstream commit 0e1d6eca5113858ed2caea61a5adc03c595f6096 ]

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.


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: default avatarEric Dumazet <>
Reported-by: default avatarsyzbot <>
Signed-off-by: default avatarDavid S. Miller <>
Signed-off-by: default avatarGreg Kroah-Hartman <>
parent 59b6d2e5
......@@ -2116,6 +2116,12 @@ 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);
err = -ENOMEM;
dev = alloc_netdev_mqs(ops->priv_size, ifname, name_assign_type,
ops->setup, num_tx_queues, num_rx_queues);
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