CVE - CVE-2024-35981

CVE-ID
CVE-2024-35981	Learn more at National Vulnerability Database (NVD) • CVSS Severity Rating • Fix Information • Vulnerable Software Versions • SCAP Mappings • CPE Information
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 eth0 hfunc 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.
References
Note: References are provided for the convenience of the reader to help distinguish between vulnerabilities. The list is not intended to be complete.
MISC:https://git.kernel.org/stable/c/059a49aa2e25c58f90b50151f109dd3c4cdb3a47 URL:https://git.kernel.org/stable/c/059a49aa2e25c58f90b50151f109dd3c4cdb3a47 MISC:https://git.kernel.org/stable/c/28e9a64638cd16bc1ecac9ff74ffeacb9fb652de URL:https://git.kernel.org/stable/c/28e9a64638cd16bc1ecac9ff74ffeacb9fb652de MISC:https://git.kernel.org/stable/c/43a71c1b4b3a6d4db857b1435d271540279fc7de URL:https://git.kernel.org/stable/c/43a71c1b4b3a6d4db857b1435d271540279fc7de MISC:https://git.kernel.org/stable/c/539a2b995a4ed93125cb0efae0f793b00ab2158b URL:https://git.kernel.org/stable/c/539a2b995a4ed93125cb0efae0f793b00ab2158b
Assigning CNA
kernel.org
Date Record Created
20240517	Disclaimer: The record creation date may reflect when the CVE ID was allocated or reserved, and does not necessarily indicate when this vulnerability was discovered, shared with the affected vendor, publicly disclosed, or updated in CVE.
Phase (Legacy)
Assigned (20240517)
Votes (Legacy)

Comments (Legacy)

Proposed (Legacy)
N/A
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