CVE-2026-89449: iommu: Fix dev_iommu memory leak when device_add fails in iommu_mock_device_add

CVE-2026-89449: iommu: Fix dev_iommu memory leak when device_add fails in iommu_mock_device_add

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@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.

The Linux kernel CVE team has assigned CVE-2026-89449 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 6.18 with commit 2a918911ed3d0841923525ed0fe707762ee78844 and fixed in 6.18.50 with commit f80f3acb69164800051ecdee871b6b006cbc2e66
	Issue introduced in 6.18 with commit 2a918911ed3d0841923525ed0fe707762ee78844 and fixed in 7.2.4 with commit eaf44262af24810d16800b988c92dfce90f73370
	Issue introduced in 6.18 with commit 2a918911ed3d0841923525ed0fe707762ee78844 and fixed in 7.3-rc1 with commit b7b0b3851474883d4aba6ed72da87141204b23e5
	Issue introduced in 6.17.3 with commit 1daf67217b0d0bf88ef7208d7fbeefe2378c6590

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-89449
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/iommu/iommu.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/f80f3acb69164800051ecdee871b6b006cbc2e66
	https://git.kernel.org/stable/c/eaf44262af24810d16800b988c92dfce90f73370
	https://git.kernel.org/stable/c/b7b0b3851474883d4aba6ed72da87141204b23e5