{"id":"CVE-2024-35981","summary":"virtio_net: Do not send RSS key if it is not supported","details":"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-\u003erss_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-\u003ebroken = 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-\u003ecvq, &tmp) &&\n\t     !virtqueue_is_broken(vi-\u003ecvq))\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-\u003ebroken`, 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.","modified":"2026-04-16T04:35:10.490188272Z","published":"2024-05-20T09:42:05.722Z","related":["SUSE-SU-2024:2135-1","SUSE-SU-2024:2203-1","SUSE-SU-2024:2973-1","SUSE-SU-2025:20008-1","SUSE-SU-2025:20028-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/35xxx/CVE-2024-35981.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/059a49aa2e25c58f90b50151f109dd3c4cdb3a47"},{"type":"WEB","url":"https://git.kernel.org/stable/c/28e9a64638cd16bc1ecac9ff74ffeacb9fb652de"},{"type":"WEB","url":"https://git.kernel.org/stable/c/43a71c1b4b3a6d4db857b1435d271540279fc7de"},{"type":"WEB","url":"https://git.kernel.org/stable/c/539a2b995a4ed93125cb0efae0f793b00ab2158b"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/35xxx/CVE-2024-35981.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-35981"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"c7114b1249fa3b5f3a434606ba4cc89c4a27d618"},{"fixed":"539a2b995a4ed93125cb0efae0f793b00ab2158b"},{"fixed":"43a71c1b4b3a6d4db857b1435d271540279fc7de"},{"fixed":"28e9a64638cd16bc1ecac9ff74ffeacb9fb652de"},{"fixed":"059a49aa2e25c58f90b50151f109dd3c4cdb3a47"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-35981.json"}}],"schema_version":"1.7.5"}