ghsa-wm4c-jgh8-m62g
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
KVM: SVM: Flush pages under kvm->lock to fix UAF in svm_register_enc_region()
Do the cache flush of converted pages in svm_register_enc_region() before dropping kvm->lock to fix use-after-free issues where region and/or its array of pages could be freed by a different task, e.g. if userspace has __unregister_enc_region_locked() already queued up for the region.
Note, the "obvious" alternative of using local variables doesn't fully resolve the bug, as region->pages is also dynamically allocated. I.e. the region structure itself would be fine, but region->pages could be freed.
Flushing multiple pages under kvm->lock is unfortunate, but the entire flow is a rare slow path, and the manual flush is only needed on CPUs that lack coherency for encrypted memory.
{
"affected": [],
"aliases": [
"CVE-2024-35791"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-05-17T13:15:58Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SVM: Flush pages under kvm-\u003elock to fix UAF in svm_register_enc_region()\n\nDo the cache flush of converted pages in svm_register_enc_region() before\ndropping kvm-\u003elock to fix use-after-free issues where region and/or its\narray of pages could be freed by a different task, e.g. if userspace has\n__unregister_enc_region_locked() already queued up for the region.\n\nNote, the \"obvious\" alternative of using local variables doesn\u0027t fully\nresolve the bug, as region-\u003epages is also dynamically allocated. I.e. the\nregion structure itself would be fine, but region-\u003epages could be freed.\n\nFlushing multiple pages under kvm-\u003elock is unfortunate, but the entire\nflow is a rare slow path, and the manual flush is only needed on CPUs that\nlack coherency for encrypted memory.",
"id": "GHSA-wm4c-jgh8-m62g",
"modified": "2024-06-26T00:31:42Z",
"published": "2024-05-17T15:31:08Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-35791"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/12f8e32a5a389a5d58afc67728c76e61beee1ad4"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2d13b79640b147bd77c34a5998533b2021a4122d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4868c0ecdb6cfde7c70cf478c46e06bb9c7e5865"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5ef1d8c1ddbf696e47b226e11888eaf8d9e8e807"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e126b508ed2e616d679d85fca2fbe77bb48bbdd7"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f6d53d8a2617dd58c89171a6b9610c470ebda38a"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html"
}
],
"schema_version": "1.4.0",
"severity": []
}