Overview

In the Linux kernel, the following vulnerability has been resolved:

virtio_net: fix xdp_rxq_info bug after suspend/resume

The following sequence currently causes a driver bug warning when using virtio_net:

ip link set eth0 up

echo mem > /sys/power/state (or e.g. # rtcwake -s 10 -m mem)

<resume> # ip link set eth0 down

Missing register, driver bug WARNING: CPU: 0 PID: 375 at net/core/xdp.c:138 xdp_rxq_info_unreg+0x58/0x60 Call trace: xdp_rxq_info_unreg+0x58/0x60 virtnet_close+0x58/0xac __dev_close_many+0xac/0x140 __dev_change_flags+0xd8/0x210 dev_change_flags+0x24/0x64 do_setlink+0x230/0xdd0 ...

This happens because virtnet_freeze() frees the receive_queue completely (including struct xdp_rxq_info) but does not call xdp_rxq_info_unreg(). Similarly, virtnet_restore() sets up the receive_queue again but does not call xdp_rxq_info_reg().

Actually, parts of virtnet_freeze_down() and virtnet_restore_up() are almost identical to virtnet_close() and virtnet_open(): only the calls to xdp_rxq_info_(un)reg() are missing. This means that we can fix this easily and avoid such problems in the future by just calling virtnet_close()/open() from the freeze/restore handlers.

Aside from adding the missing xdp_rxq_info calls the only difference is that the refill work is only cancelled if netif_running(). However, this should not make any functional difference since the refill work should only be active if the network interface is actually up.

Affected

• Linux >= 754b8a21a96d5f11712245aef907149606b323ae < 9222672fa6370f0ec3d899662cb8680e9282fc4c
• Linux >= 754b8a21a96d5f11712245aef907149606b323ae < 8c7a32b7c15555beddc5810c3334d9cefff061bf
• Linux >= 754b8a21a96d5f11712245aef907149606b323ae < 340fbdc8011f2dc678f622c5ce1cbb5ab8305de7
• Linux >= 754b8a21a96d5f11712245aef907149606b323ae < 8d7fe9ad6fddc2af8bde4b921b4f8fab231ed38c
• Linux >= 754b8a21a96d5f11712245aef907149606b323ae < 57ee40f1b198b59d43c216fbc4672f9300d3c8b0
• Linux >= 754b8a21a96d5f11712245aef907149606b323ae < 8af52fe9fd3bf5e7478da99193c0632276e1dfce
• Linux 4.16

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.