ghsa-866j-mv4h-26jh
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
net: veth: clear GRO when clearing XDP even when down
veth sets NETIF_F_GRO automatically when XDP is enabled, because both features use the same NAPI machinery.
The logic to clear NETIF_F_GRO sits in veth_disable_xdp() which is called both on ndo_stop and when XDP is turned off. To avoid the flag from being cleared when the device is brought down, the clearing is skipped when IFF_UP is not set. Bringing the device down should indeed not modify its features.
Unfortunately, this means that clearing is also skipped when XDP is disabled while the device is down. And there's nothing on the open path to bring the device features back into sync. IOW if user enables XDP, disables it and then brings the device up we'll end up with a stray GRO flag set but no NAPI instances.
We don't depend on the GRO flag on the datapath, so the datapath won't crash. We will crash (or hang), however, next time features are sync'ed (either by user via ethtool or peer changing its config). The GRO flag will go away, and veth will try to disable the NAPIs. But the open path never created them since XDP was off, the GRO flag was a stray. If NAPI was initialized before we'll hang in napi_disable(). If it never was we'll crash trying to stop uninitialized hrtimer.
Move the GRO flag updates to the XDP enable / disable paths, instead of mixing them with the ndo_open / ndo_close paths.
{
"affected": [],
"aliases": [
"CVE-2024-26803"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-04-04T09:15:09Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: veth: clear GRO when clearing XDP even when down\n\nveth sets NETIF_F_GRO automatically when XDP is enabled,\nbecause both features use the same NAPI machinery.\n\nThe logic to clear NETIF_F_GRO sits in veth_disable_xdp() which\nis called both on ndo_stop and when XDP is turned off.\nTo avoid the flag from being cleared when the device is brought\ndown, the clearing is skipped when IFF_UP is not set.\nBringing the device down should indeed not modify its features.\n\nUnfortunately, this means that clearing is also skipped when\nXDP is disabled _while_ the device is down. And there\u0027s nothing\non the open path to bring the device features back into sync.\nIOW if user enables XDP, disables it and then brings the device\nup we\u0027ll end up with a stray GRO flag set but no NAPI instances.\n\nWe don\u0027t depend on the GRO flag on the datapath, so the datapath\nwon\u0027t crash. We will crash (or hang), however, next time features\nare sync\u0027ed (either by user via ethtool or peer changing its config).\nThe GRO flag will go away, and veth will try to disable the NAPIs.\nBut the open path never created them since XDP was off, the GRO flag\nwas a stray. If NAPI was initialized before we\u0027ll hang in napi_disable().\nIf it never was we\u0027ll crash trying to stop uninitialized hrtimer.\n\nMove the GRO flag updates to the XDP enable / disable paths,\ninstead of mixing them with the ndo_open / ndo_close paths.",
"id": "GHSA-866j-mv4h-26jh",
"modified": "2024-04-04T09:30:36Z",
"published": "2024-04-04T09:30:36Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-26803"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/16edf51f33f52dff70ed455bc40a6cc443c04664"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7985d73961bbb4e726c1be7b9cd26becc7be8325"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/8f7a3894e58e6f5d5815533cfde60e3838947941"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f011c103e654d83dc85f057a7d1bd0960d02831c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/fe9f801355f0b47668419f30f1fac1cf4539e736"
}
],
"schema_version": "1.4.0",
"severity": []
}
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- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.