{"id":"CVE-2024-46762","state":"PUBLISHED","title":"xen: privcmd: Fix possible access to a freed kirqfd instance","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nxen: privcmd: Fix possible access to a freed kirqfd instance\n\nNothing prevents simultaneous ioctl calls to privcmd_irqfd_assign() and\nprivcmd_irqfd_deassign(). If that happens, it is possible that a kirqfd\ncreated and added to the irqfds_list by privcmd_irqfd_assign() may get\nremoved by another thread executing privcmd_irqfd_deassign(), while the\nformer is still using it after dropping the locks.\n\nThis can lead to a situation where an already freed kirqfd instance may\nbe accessed and cause kernel oops.\n\nUse SRCU locking to prevent the same, as is done for the KVM\nimplementation for irqfds.","publishedAt":"2024-09-18T07:12:21.854Z","updatedAt":"2026-08-05T11:38:24.559Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"f8941e6c4c712948663ec5d7bbb546f1a0f4e3f6","status":"affected","lessThan":"e997b357b13a7d95de31681fc54fcc34235fa527","versionType":"git"},{"version":"f8941e6c4c712948663ec5d7bbb546f1a0f4e3f6","status":"affected","lessThan":"112fd2f02b308564724b8e81006c254d20945c4b","versionType":"git"},{"version":"f8941e6c4c712948663ec5d7bbb546f1a0f4e3f6","status":"affected","lessThan":"611ff1b1ae989a7bcce3e2a8e132ee30e968c557","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/xen/privcmd.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.6","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.6","versionType":"semver"},{"version":"6.6.51","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.10.10","status":"unaffected","lessThanOrEqual":"6.10.*","versionType":"semver"},{"version":"6.11","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/xen/privcmd.c"]}],"references":["https://git.kernel.org/stable/c/e997b357b13a7d95de31681fc54fcc34235fa527","https://git.kernel.org/stable/c/112fd2f02b308564724b8e81006c254d20945c4b","https://git.kernel.org/stable/c/611ff1b1ae989a7bcce3e2a8e132ee30e968c557"],"weaknesses":[],"ingestedAt":"2026-10-29T20:07:47.831Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2024/46xxx/CVE-2024-46762.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2024-46762","state":"PUBLISHED","datePublished":"2024-09-18T07:12:21.854Z","dateUpdated":"2026-08-05T11:38:24.559Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2024-09-11T15:12:18.272Z"},"containers":{"cna":{"title":"xen: privcmd: Fix possible access to a freed kirqfd instance","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nxen: privcmd: Fix possible access to a freed kirqfd instance\n\nNothing prevents simultaneous ioctl calls to privcmd_irqfd_assign() and\nprivcmd_irqfd_deassign(). If that happens, it is possible that a kirqfd\ncreated and added to the irqfds_list by privcmd_irqfd_assign() may get\nremoved by another thread executing privcmd_irqfd_deassign(), while the\nformer is still using it after dropping the locks.\n\nThis can lead to a situation where an already freed kirqfd instance may\nbe accessed and cause kernel oops.\n\nUse SRCU locking to prevent the same, as is done for the KVM\nimplementation for irqfds."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"f8941e6c4c712948663ec5d7bbb546f1a0f4e3f6","status":"affected","lessThan":"e997b357b13a7d95de31681fc54fcc34235fa527","versionType":"git"},{"version":"f8941e6c4c712948663ec5d7bbb546f1a0f4e3f6","status":"affected","lessThan":"112fd2f02b308564724b8e81006c254d20945c4b","versionType":"git"},{"version":"f8941e6c4c712948663ec5d7bbb546f1a0f4e3f6","status":"affected","lessThan":"611ff1b1ae989a7bcce3e2a8e132ee30e968c557","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/xen/privcmd.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.6","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.6","versionType":"semver"},{"version":"6.6.51","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.10.10","status":"unaffected","lessThanOrEqual":"6.10.*","versionType":"semver"},{"version":"6.11","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/xen/privcmd.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/e997b357b13a7d95de31681fc54fcc34235fa527"},{"url":"https://git.kernel.org/stable/c/112fd2f02b308564724b8e81006c254d20945c4b"},{"url":"https://git.kernel.org/stable/c/611ff1b1ae989a7bcce3e2a8e132ee30e968c557"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The vulnerability is reached only through `ioctl(IOCTL_PRIVCMD_IRQFD)` on the `/dev/xen/privcmd` character device, requiring local access to the system. No remote or adjacent-network path exists to `privcmd_ioctl_irqfd()`.\nAC:L - The attacker controls both sides of the race, issuing the assign and deassign ioctls concurrently from its own threads on the same eventfd, and can retry in a tight loop; the window is further widened by the workqueue handoff to `irqfd_shutdown()` and the preemptible `HYPERVISOR_dm_op()` call in `irqfd_inject()`.\nPR:L - `privcmd_ioctl()` performs no capability check whatsoever — only the device-node permission gates access — and the `IOCTL_PRIVCMD_RESTRICT` design explicitly hands a privcmd fd to deprivileged device-model/virtio-backend daemons, which is exactly the scenario the irqfd interface was built for, so an unprivileged local process holding that fd can trigger the UAF.\nUI:N - The attacker performs the entire sequence itself with two concurrent ioctls on descriptors it owns; no action by any other user or victim process is needed.\nS:U - The use-after-free corrupts kernel memory in the same domain that hosts the calling process, giving standard local kernel privilege escalation rather than crossing the Xen guest/host or IOMMU boundary.\nC:H - The freed `privcmd_kernel_irqfd` is left registered in the eventfd wait queue and is re-read (`kirqfd->eventfd`, `kirqfd->xbufs`, `wait->func`) after `kfree()`, and the attacker chooses the allocation size via the unbounded `irqfd->size`, so resprayed slab contents can be leveraged into arbitrary kernel memory disclosure.\nI:H - `add_wait_queue_priority()` writes list pointers into the freed chunk and `kirqfd->error = rc` writes into it as well, while the dangling wait-queue entry causes a later `eventfd_signal()` to call a function pointer read from attacker-resprayed memory — a control-flow hijack / arbitrary-write primitive.\nA:H - The commit itself states the freed `kirqfd` access \"can lead to a situation where an already freed kirqfd instance may be accessed and cause kernel oops\"; the corrupted wait-queue list and freed `eventfd_ctx` reliably panic the kernel even without full exploitation."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T11:38:24.559Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6","versionEndExcluding":"6.6.51"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6","versionEndExcluding":"6.10.10"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6","versionEndExcluding":"6.11"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2024-09-29T14:43:33.478974Z","id":"CVE-2024-46762","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2024-09-29T14:43:47.331Z"}}]}}}