{"cve":"CVE-2024-35981","nvd":{"published":"2024-05-20T10:15:12.617","modified":"2026-06-17T07:35:52.327","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nvirtio_net: Do not send RSS key if it is not supported\n\nThere is a bug when setting the RSS options in virtio_net that can break\nthe whole machine, getting the kernel into an infinite loop.\n\nRunning the following command in any QEMU virtual machine with virtionet\nwill reproduce this problem:\n\n    # ethtool -X eth0  hfunc toeplitz\n\nThis is how the problem happens:\n\n1) ethtool_set_rxfh() calls virtnet_set_rxfh()\n\n2) virtnet_set_rxfh() calls virtnet_commit_rss_command()\n\n3) virtnet_commit_rss_command() populates 4 entries for the rss\nscatter-gather\n\n4) Since the command above does not have a key, then the last\nscatter-gatter entry will be zeroed, since rss_key_size == 0.\nsg_buf_size = vi->rss_key_size;\n\n5) This buffer is passed to qemu, but qemu is not happy with a buffer\nwith zero length, and do the following in virtqueue_map_desc() (QEMU\nfunction):\n\n  if (!sz) {\n      virtio_error(vdev, \"virtio: zero sized buffers are not allowed\");\n\n6) virtio_error() (also QEMU function) set the device as broken\n\n    vdev->broken = true;\n\n7) Qemu bails out, and do not repond this crazy kernel.\n\n8) The kernel is waiting for the response to come back (function\nvirtnet_send_command())\n\n9) The kernel is waiting doing the following :\n\n      while (!virtqueue_get_buf(vi->cvq, &tmp) &&\n\t     !virtqueue_is_broken(vi->cvq))\n\t      cpu_relax();\n\n10) None of the following functions above is true, thus, the kernel\nloops here forever. Keeping in mind that virtqueue_is_broken() does\nnot look at the qemu `vdev->broken`, so, it never realizes that the\nvitio is broken at QEMU side.\n\nFix it by not sending RSS commands if the feature is not available in\nthe device.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":["CWE-835"],"references":["https://git.kernel.org/stable/c/059a49aa2e25c58f90b50151f109dd3c4cdb3a47","https://git.kernel.org/stable/c/28e9a64638cd16bc1ecac9ff74ffeacb9fb652de","https://git.kernel.org/stable/c/43a71c1b4b3a6d4db857b1435d271540279fc7de","https://git.kernel.org/stable/c/539a2b995a4ed93125cb0efae0f793b00ab2158b","https://git.kernel.org/stable/c/059a49aa2e25c58f90b50151f109dd3c4cdb3a47"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:50:30.954589733+00:00"},"epss":{"cve":"CVE-2024-35981","score":0.00227,"percentile":0.13431,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}