{
  "threat_severity" : "Moderate",
  "public_date" : "2025-10-15T00:00:00Z",
  "bugzilla" : {
    "description" : "kernel: iommufd: Fix race during abort for file descriptors",
    "id" : "2404107",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2404107"
  },
  "cvss3" : {
    "cvss3_base_score" : "7.4",
    "cvss3_scoring_vector" : "CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
    "status" : "verified"
  },
  "cwe" : "CWE-416",
  "details" : [ "In the Linux kernel, the following vulnerability has been resolved:\niommufd: Fix race during abort for file descriptors\nfput() doesn't actually call file_operations release() synchronously, it\nputs the file on a work queue and it will be released eventually.\nThis is normally fine, except for iommufd the file and the iommufd_object\nare tied to gether. The file has the object as it's private_data and holds\na users refcount, while the object is expected to remain alive as long as\nthe file is.\nWhen the allocation of a new object aborts before installing the file it\nwill fput() the file and then go on to immediately kfree() the obj. This\ncauses a UAF once the workqueue completes the fput() and tries to\ndecrement the users refcount.\nFix this by putting the core code in charge of the file lifetime, and call\n__fput_sync() during abort to ensure that release() is called before\nkfree. __fput_sync() is a bit too tricky to open code in all the object\nimplementations. Instead the objects tell the core code where the file\npointer is and the core will take care of the life cycle.\nIf the object is successfully allocated then the file will hold a users\nrefcount and the iommufd_object cannot be destroyed.\nIt is worth noting that close(); ioctl(IOMMU_DESTROY); doesn't have an\nissue because close() is already using a synchronous version of fput().\nThe UAF looks like this:\nBUG: KASAN: slab-use-after-free in iommufd_eventq_fops_release+0x45/0xc0 drivers/iommu/iommufd/eventq.c:376\nWrite of size 4 at addr ffff888059c97804 by task syz.0.46/6164\nCPU: 0 UID: 0 PID: 6164 Comm: syz.0.46 Not tainted syzkaller #0 PREEMPT(full)\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025\nCall Trace:\n<TASK>\n__dump_stack lib/dump_stack.c:94 [inline]\ndump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120\nprint_address_description mm/kasan/report.c:378 [inline]\nprint_report+0xcd/0x630 mm/kasan/report.c:482\nkasan_report+0xe0/0x110 mm/kasan/report.c:595\ncheck_region_inline mm/kasan/generic.c:183 [inline]\nkasan_check_range+0x100/0x1b0 mm/kasan/generic.c:189\ninstrument_atomic_read_write include/linux/instrumented.h:96 [inline]\natomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:400 [inline]\n__refcount_dec include/linux/refcount.h:455 [inline]\nrefcount_dec include/linux/refcount.h:476 [inline]\niommufd_eventq_fops_release+0x45/0xc0 drivers/iommu/iommufd/eventq.c:376\n__fput+0x402/0xb70 fs/file_table.c:468\ntask_work_run+0x14d/0x240 kernel/task_work.c:227\nresume_user_mode_work include/linux/resume_user_mode.h:50 [inline]\nexit_to_user_mode_loop+0xeb/0x110 kernel/entry/common.c:43\nexit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]\nsyscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]\nsyscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]\ndo_syscall_64+0x41c/0x4c0 arch/x86/entry/syscall_64.c:100\nentry_SYSCALL_64_after_hwframe+0x77/0x7f", "A flaw was found in the Linux kernel such that the IOMMU file-descriptor subsystem, when aborting the allocation of a new object before installing the file descriptor, the code calls fput() on the file and then immediately frees the associated object (kfree()), but the object is still referenced by the file descriptor on a deferred workqueue. This results in a use-after-free (UAF) condition which may lead to memory corruption or system instability" ],
  "affected_release" : [ {
    "product_name" : "Red Hat Enterprise Linux 10",
    "release_date" : "2026-01-12T00:00:00Z",
    "advisory" : "RHSA-2026:0453",
    "cpe" : "cpe:/o:redhat:enterprise_linux:10.1",
    "package" : "kernel-0:6.12.0-124.27.1.el10_1"
  }, {
    "product_name" : "Red Hat Enterprise Linux 10.0 Extended Update Support",
    "release_date" : "2025-12-17T00:00:00Z",
    "advisory" : "RHSA-2025:23250",
    "cpe" : "cpe:/o:redhat:enterprise_linux_eus:10.0",
    "package" : "kernel-0:6.12.0-55.50.1.el10_0"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "release_date" : "2025-12-17T00:00:00Z",
    "advisory" : "RHSA-2025:23241",
    "cpe" : "cpe:/a:redhat:enterprise_linux:9",
    "package" : "kernel-0:5.14.0-611.16.1.el9_7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "release_date" : "2025-12-17T00:00:00Z",
    "advisory" : "RHSA-2025:23241",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9",
    "package" : "kernel-0:5.14.0-611.16.1.el9_7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9.6 Extended Update Support",
    "release_date" : "2025-12-09T00:00:00Z",
    "advisory" : "RHSA-2025:22802",
    "cpe" : "cpe:/a:redhat:rhel_eus:9.6",
    "package" : "kernel-0:5.14.0-570.72.1.el9_6"
  } ],
  "package_state" : [ {
    "product_name" : "Red Hat Enterprise Linux 6",
    "fix_state" : "Not affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:6"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Not affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Not affected",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "fix_state" : "Not affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "fix_state" : "Not affected",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "fix_state" : "Affected",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9"
  } ],
  "references" : [ "https://www.cve.org/CVERecord?id=CVE-2025-39966\nhttps://nvd.nist.gov/vuln/detail/CVE-2025-39966\nhttps://lore.kernel.org/linux-cve-announce/2025101553-CVE-2025-39966-736b@gregkh/T" ],
  "name" : "CVE-2025-39966",
  "mitigation" : {
    "value" : "Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.",
    "lang" : "en:us"
  },
  "csaw" : false
}