There are some problems with network device ifindex handling in the core and veth driver.
* Network device index (ifindex) is signed int, but only values > 0 consodered to be valid. However it is possible for userspace to supply negative ifindex value using following command: # ip link add dev dummy2 index -100 up type dummy # ip link sh dev dummy2 Device "dummy2" does not exist. # ip li sh |tail -n2 -100: dummy2: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue \ state UNKNOWN mode DEFAULT group default link/ether 7e:77:1b:49:50:de brd ff:ff:ff:ff:ff:ff * It is possible to hit infinite loop when number of ifindex in some network namespace get exchausted. # There should be plenty of RAM to create INT_MAX netdev. # Hitting OOM is much likely with such huge number, but anyway. for ((i = 1; i <= 0x7fffffff; i++)); do ifname="dummy$i"; [ ! -d "/sys/class/net/$ifname" ] || continue ip link add dev "$ifname" index "$i" type dummy done * (minor) check for dev->ifindex being greater than zero. Patches in this series tries to address these problems. Serhey Popovych (3): dev: Prevent creating network devices with negative ifindex dev: Avoid infinite loop on network device index exhaustion veth: Set ifindex only if given and not negative drivers/net/veth.c | 2 +- net/core/dev.c | 30 ++++++++++++++++++++++-------- 2 files changed, 23 insertions(+), 9 deletions(-) -- 1.8.3.1