发布于3月6日3月6日 Members Ubuntu: (Multiple Advisories) (CVE-2024-35981): Linux kernel vulnerabilities Severity 5 CVSS (AV:L/AC:L/Au:S/C:N/I:N/A:C) Published 05/20/2024 Created 07/12/2024 Added 07/12/2024 Modified 01/30/2025 Description In the Linux kernel, the following vulnerability has been resolved: virtio_net: Do not send RSS key if it is not supported There is a bug when setting the RSS options in virtio_net that can break the whole machine, getting the kernel into an infinite loop. Running the following command in any QEMU virtual machine with virtionet will reproduce this problem: # ethtool -X eth0hfunc toeplitz This is how the problem happens: 1) ethtool_set_rxfh() calls virtnet_set_rxfh() 2) virtnet_set_rxfh() calls virtnet_commit_rss_command() 3) virtnet_commit_rss_command() populates 4 entries for the rss scatter-gather 4) Since the command above does not have a key, then the last scatter-gatter entry will be zeroed, since rss_key_size == 0. sg_buf_size = vi->rss_key_size; 5) This buffer is passed to qemu, but qemu is not happy with a buffer with zero length, and do the following in virtqueue_map_desc() (QEMU function): if (!sz) { virtio_error(vdev, "virtio: zero sized buffers are not allowed"); 6) virtio_error() (also QEMU function) set the device as broken vdev->broken = true; 7) Qemu bails out, and do not repond this crazy kernel. 8) The kernel is waiting for the response to come back (function virtnet_send_command()) 9) The kernel is waiting doing the following : while (!virtqueue_get_buf(vi->cvq, &tmp) && !virtqueue_is_broken(vi->cvq)) cpu_relax(); 10) None of the following functions above is true, thus, the kernel loops here forever. Keeping in mind that virtqueue_is_broken() does not look at the qemu `vdev->broken`, so, it never realizes that the vitio is broken at QEMU side. Fix it by not sending RSS commands if the feature is not available in the device. Solution(s) ubuntu-upgrade-linux-image-6-8-0-1006-gke ubuntu-upgrade-linux-image-6-8-0-1007-intel ubuntu-upgrade-linux-image-6-8-0-1007-raspi ubuntu-upgrade-linux-image-6-8-0-1008-ibm ubuntu-upgrade-linux-image-6-8-0-1008-oem ubuntu-upgrade-linux-image-6-8-0-1008-oracle ubuntu-upgrade-linux-image-6-8-0-1008-oracle-64k ubuntu-upgrade-linux-image-6-8-0-1009-nvidia ubuntu-upgrade-linux-image-6-8-0-1009-nvidia-64k ubuntu-upgrade-linux-image-6-8-0-1010-azure ubuntu-upgrade-linux-image-6-8-0-1010-azure-fde ubuntu-upgrade-linux-image-6-8-0-1010-gcp ubuntu-upgrade-linux-image-6-8-0-1011-aws ubuntu-upgrade-linux-image-6-8-0-38-generic ubuntu-upgrade-linux-image-6-8-0-38-generic-64k ubuntu-upgrade-linux-image-6-8-0-38-lowlatency ubuntu-upgrade-linux-image-6-8-0-38-lowlatency-64k ubuntu-upgrade-linux-image-aws ubuntu-upgrade-linux-image-azure ubuntu-upgrade-linux-image-azure-fde ubuntu-upgrade-linux-image-gcp ubuntu-upgrade-linux-image-generic ubuntu-upgrade-linux-image-generic-64k ubuntu-upgrade-linux-image-generic-64k-hwe-24-04 ubuntu-upgrade-linux-image-generic-hwe-24-04 ubuntu-upgrade-linux-image-generic-lpae ubuntu-upgrade-linux-image-gke ubuntu-upgrade-linux-image-ibm ubuntu-upgrade-linux-image-ibm-classic ubuntu-upgrade-linux-image-ibm-lts-24-04 ubuntu-upgrade-linux-image-intel ubuntu-upgrade-linux-image-kvm ubuntu-upgrade-linux-image-lowlatency ubuntu-upgrade-linux-image-lowlatency-64k ubuntu-upgrade-linux-image-nvidia ubuntu-upgrade-linux-image-nvidia-64k ubuntu-upgrade-linux-image-oem-24-04 ubuntu-upgrade-linux-image-oem-24-04a ubuntu-upgrade-linux-image-oracle ubuntu-upgrade-linux-image-oracle-64k ubuntu-upgrade-linux-image-raspi ubuntu-upgrade-linux-image-virtual ubuntu-upgrade-linux-image-virtual-hwe-24-04 References https://attackerkb.com/topics/cve-2024-35981 CVE - 2024-35981 USN-6893-1 USN-6893-2 USN-6893-3 USN-6918-1
