cbcvebase.
CVE-2025-39966
published 2025-10-15

CVE-2025-39966: In the Linux kernel, the following vulnerability has been resolved: iommufd: Fix race during abort for file descriptors fput() doesn't actually call…

PriorityP432high7CVSS 3.1
AVLACHPRLUINSUCHIHAH
EPSS
0.10%
1.1th percentile
In the Linux kernel, the following vulnerability has been resolved: iommufd: Fix race during abort for file descriptors fput() doesn't actually call file_operations release() synchronously, it puts the file on a work queue and it will be released eventually. This is normally fine, except for iommufd the file and the iommufd_object are tied to gether. The file has the object as it's private_data and holds a users refcount, while the object is expected to remain alive as long as the file is. When the allocation of a new object aborts before installing the file it will fput() the file and then go on to immediately kfree() the obj. This causes a UAF once the workqueue completes the fput() and tries to decrement the users refcount. Fix this by putting the core code in charge of the file lifetime, and call __fput_sync() during abort to ensure that release() is called before kfree. __fput_sync() is a bit too tricky to open code in all the object implementations. Instead the objects tell the core code where the file pointer is and the core will take care of the life cycle. If the object is successfully allocated then the file will hold a users refcount and the iommufd_object cannot be destroyed. It is worth noting that close(); ioctl(IOMMU_DESTROY); doesn't have an issue because close() is already using a synchronous version of fput(). The UAF looks like this: BUG: KASAN: slab-use-after-free in iommufd_eventq_fops_release+0x45/0xc0 drivers/iommu/iommufd/eventq.c:376 Write of size 4 at addr ffff888059c97804 by task syz.0.46/6164 CPU: 0 UID: 0 PID: 6164 Comm: syz.0.46 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xcd/0x630 mm/kasan/report.c:482 kasan_report+0xe0/0x110 mm/kasan/report.c:595 check_region_inline mm/k

Affected

16 ranges
VendorProductVersion rangeFixed in
debianlinux< linux 6.16.10-1 (forky)linux 6.16.10-1 (forky)
linuxlinux——
linuxlinux>= 07838f7fd529c8a6de44b601d4b7057e6c8d36ed < 17195a7d754a5c6a31888702ca93f6f08f3383ad17195a7d754a5c6a31888702ca93f6f08f3383ad
linuxlinux>= 07838f7fd529c8a6de44b601d4b7057e6c8d36ed < e4825368285e33d6360c6c6a6a10d2d83da06e55e4825368285e33d6360c6c6a6a10d2d83da06e55
linuxlinux>= 07838f7fd529c8a6de44b601d4b7057e6c8d36ed < 4e034bf045b12852a24d5d33f2451850818ba0c14e034bf045b12852a24d5d33f2451850818ba0c1
linuxlinux_kernel——
linuxlinux_kernel——
linuxlinux_kernel——
linuxlinux_kernel——
linuxlinux_kernel——
linuxlinux_kernel——
linuxlinux_kernel——
linuxlinux_kernel>= 0 < 6.12.57-16.12.57-1
linuxlinux_kernel>= 0 < 6.16.10-16.16.10-1
linuxlinux_kernel>= 6.11 < 6.12.506.12.50
linuxlinux_kernel>= 6.13 < 6.16.106.16.10

CVSS provenance

nvdv3.17.0HIGHCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
osv7.0HIGH
vendor_debian7.0LOW
vendor_redhat7.0HIGH
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