vsock/virtio: flush works in dependency order

Overview

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

vsock/virtio: flush works in dependency order

virtio_vsock_remove() stops the virtqueues and then flushes each work item before freeing the enclosing virtio_vsock. The current order does not account for dependencies between those items: tx_work may queue send_pkt_work, and send_pkt_work may queue rx_work.

In particular, send_pkt_work can set restart_rx and release tx_lock. The remove path can then stop the queues and flush rx_work before send_pkt_work queues it. Although the later send_pkt_work flush waits for that producer to finish, nothing waits for the newly queued rx_work, so kfree(vsock) can race with it.

KASAN reported:

BUG: KASAN: slab-use-after-free in virtio_transport_rx_work+0x487/0x4b0 Read of size 8 at addr ffff888114c2b008 by task kworker/1:1/47 Workqueue: virtio_vsock virtio_transport_rx_work Call Trace: virtio_transport_rx_work+0x487/0x4b0 process_one_work+0x688/0x1120 worker_thread+0x45b/0xd10 Allocated by task 1: virtio_vsock_probe+0xef/0x6b0 Freed by task 84: kfree+0x131/0x3c0 virtio_vsock_remove+0xd1/0x100

Flush the works in producer-to-consumer order. virtio_vsock_vqs_del() has already disabled the queue callbacks and cleared the run flags, so after tx_work and send_pkt_work are drained, no source remains that can queue rx_work after its flush.

Affected

• Linux >= 0ea9e1d3a9e3ef7d2a1462d3de6b95131dc7d872 < e059a14c1067bcc4f7b1947cd09f2baab98e340f
• Linux >= 0ea9e1d3a9e3ef7d2a1462d3de6b95131dc7d872 < 531e2ac2dab1ab90a16427c4f9c86663633e9487
• Linux >= 0ea9e1d3a9e3ef7d2a1462d3de6b95131dc7d872 < f3313d952fc380cff53db9a28451a8807aa67b43
• Linux >= 0ea9e1d3a9e3ef7d2a1462d3de6b95131dc7d872 < b9cb4e8ba71c9fbd935d66baa71bbb0b87192c94
• Linux >= 0ea9e1d3a9e3ef7d2a1462d3de6b95131dc7d872 < 2187a56f2fd1715d54daed6392809223c60544f3
• Linux >= 0ea9e1d3a9e3ef7d2a1462d3de6b95131dc7d872 < 165a330a68b5f299d8735f0194c314cb2e571269
• Linux >= 0ea9e1d3a9e3ef7d2a1462d3de6b95131dc7d872 < da5e9f08714c19ba04e6863aca69d40f042f2e04
• Linux >= 0ea9e1d3a9e3ef7d2a1462d3de6b95131dc7d872 < 728836ebca239810f164262b10211ef59182f811
• Linux 4.8

Remediation

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

Vendor advisories

• Red Hat VEX · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, … · updated 2026-09-14 · vex