Affected: Alpaquita:23: linux-lts, Alpaquita:25: linux-lts, Alpaquita:stream: linux-lts

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.

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.

kernel-devel-7.2.6-1.1 on GA media

Affected: Ubuntu:Pro:14.04:LTS: linux-azure, Ubuntu:Pro:16.04:LTS: linux-aws-hwe, Ubuntu:Pro:16.04:LTS: linux-azure, Ubuntu:Pro:16.04:LTS: linux-gcp, Ubuntu:Pro:16.04:LTS: linux-hwe, Ubuntu:16.04:LTS: linux-hwe-edge, Ubuntu:Pro:16.04:LTS: linux-oracle, Ubuntu:Pro:18.04:LTS: linux, Ubuntu:Pro:18.04:LTS: linux-aws, Ubuntu:18.04:LTS: linux-aws-5.0 and 239 more

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.

Ein Angreifer kann mehrere Schwachstellen im Linux Kernel ausnutzen, um Sicherheitsmaßnahmen zu umgehen, Daten oder den Systemzustand zu manipulieren, Denial-of-Service-Zustände herbeizuführen oder andere, nicht näher spezifizierte Angriffe durchzuführen.