CVE-2026-89449

Received Received - Intake

Memory Leak in Linux Kernel IOMMU Subsystem

Publication date: 2026-09-11

Last updated on: 2026-09-11

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: iommu: Fix dev_iommu memory leak when device_add fails in iommu_mock_device_add iommu_mock_device_add() first calls iommu_fwspec_init(), which on success allocates both dev->iommu (via dev_iommu_get()) and dev->iommu->fwspec. If the subsequent device_add(dev) call fails, the error path only calls iommu_fwspec_free(dev), which frees fwspec but leaves dev->iommu still allocated. This triggers the following kmemleak report when fuzzing with Syzkaller: BUG: memory leak unreferenced object 0xffff888011e0a200 (size 192): comm "syz.1.1695", pid 24885, jiffies 4295222527 hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 ad 4e ad de .............N.. ff ff ff ff 00 00 00 00 ff ff ff ff ff ff ff ff ................ backtrace (crc 25df5bb3): kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline] slab_post_alloc_hook mm/slub.c:4575 [inline] slab_alloc_node mm/slub.c:4899 [inline] __kmalloc_cache_noprof+0x47a/0x710 mm/slub.c:5415 kmalloc_noprof include/linux/slab.h:950 [inline] kzalloc_noprof include/linux/slab.h:1188 [inline] dev_iommu_get+0x10c/0x1a0 drivers/iommu/iommu.c:408 iommu_fwspec_init+0x288/0x4d0 drivers/iommu/iommu.c:3087 iommu_mock_device_add+0x46/0xb0 drivers/iommu/iommu.c:385 mock_dev_create drivers/iommu/iommufd/selftest.c:1025 [inline] iommufd_test_mock_domain drivers/iommu/iommufd/selftest.c:1066 [inline] iommufd_test+0x2f8a/0x6190 drivers/iommu/iommufd/selftest.c:2072 iommufd_fops_ioctl+0x367/0x540 drivers/iommu/iommufd/main.c:533 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x116/0x800 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Fix this by calling dev_iommu_free(dev) instead of iommu_fwspec_free(dev) in the device_add() failure path. dev_iommu_free() frees both fwspec and the outer dev_iommu struct and clears dev->iommu.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-09-11

Last Modified

2026-09-11

Generated

2026-10-02

AI Q&A

2026-09-12

EPSS Evaluated

2026-10-01

NVD

CVE-2026-89449

EUVD

EUVD-2026-76355

Affected Vendors & Products

Vendor	Product	Version / Range
linux_kernel	linux_kernel	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability in the Linux kernel involves a memory leak in the IOMMU (Input-Output Memory Management Unit) subsystem. When a device fails to be added via device_add(), the error handling code only frees part of the allocated memory (dev->iommu->fwspec) but leaves the outer dev->iommu structure allocated. This causes a memory leak that can be detected by tools like kmemleak.

Detection Guidance

This vulnerability is specific to the Linux kernel's IOMMU subsystem and may not have direct network detection methods. It involves a memory leak in the iommu_mock_device_add function when device_add fails. Monitoring for memory leaks using tools like kmemleak or checking kernel logs for memory allocation errors may help detect this issue.

Impact Analysis

The memory leak could lead to gradual exhaustion of kernel memory over time, potentially causing system instability or crashes. It may also be exploited in fuzzing scenarios to trigger memory-related issues, though it does not directly allow privilege escalation or data theft.

Compliance Impact

This vulnerability causes a memory leak in the Linux kernel's IOMMU subsystem when device initialization fails. While it does not directly impact data privacy or security controls required by standards like GDPR or HIPAA, memory leaks can lead to system instability or denial-of-service conditions, which may indirectly affect compliance by disrupting required security measures or data processing operations.

Mitigation Strategies

Apply the kernel patch that fixes the memory leak by replacing iommu_fwspec_free(dev) with dev_iommu_free(dev) in the device_add failure path. Update to a Linux kernel version that includes this fix. Monitor system memory usage and kernel logs for signs of memory leaks.

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