CVE-2026-74574: dmaengine: idxd: fix fdev setup failure cleanup in idxd_cdev_open()

From: Greg Kroah-Hartman <[email protected]>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

dmaengine: idxd: fix fdev setup failure cleanup in idxd_cdev_open()

The failed_dev_add and failed_dev_name paths drop the file-device
reference while wq->wq_lock is still held. If put_device(fdev) drops the
last reference, idxd_file_dev_release() runs synchronously and tries to
take wq->wq_lock again, deadlocking.

Those paths also fall through into the later ctx cleanup labels even
though idxd_file_dev_release() owns that cleanup and frees ctx. This can
make idxd_xa_pasid_remove(ctx) and kfree(ctx) operate on a freed context.

Move idxd_wq_get() before file-device setup can fail, since the release
callback always calls idxd_wq_put(). Then unlock wq->wq_lock before
put_device(fdev) and return directly from the file-device setup failure
path, leaving ctx cleanup to the release callback.

The Linux kernel CVE team has assigned CVE-2026-74574 to this issue.


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

	Issue introduced in 6.4 with commit e6fd6d7e5f0fe4a17a08e892afb5db800e7794ec and fixed in 6.6.151 with commit 778ccbded2c8749c5be7f0dfa04fc9977a36fb7e
	Issue introduced in 6.4 with commit e6fd6d7e5f0fe4a17a08e892afb5db800e7794ec and fixed in 6.12.103 with commit 8d5d28285728be47c82fdf1c48be4268293c90e7
	Issue introduced in 6.4 with commit e6fd6d7e5f0fe4a17a08e892afb5db800e7794ec and fixed in 6.18.44 with commit 0679c0c189d2548f00e1bac95be28e2df5c6c7f7
	Issue introduced in 6.4 with commit e6fd6d7e5f0fe4a17a08e892afb5db800e7794ec and fixed in 7.1.8 with commit 6e26a41c4c1a706edaaa7c7dffc6b3b945707a55
	Issue introduced in 6.4 with commit e6fd6d7e5f0fe4a17a08e892afb5db800e7794ec and fixed in 7.2-rc6 with commit ee1d7274102285d78a53161fc705a8d8cd40b066

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-2026-74574
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/dma/idxd/cdev.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/778ccbded2c8749c5be7f0dfa04fc9977a36fb7e
	https://git.kernel.org/stable/c/8d5d28285728be47c82fdf1c48be4268293c90e7
	https://git.kernel.org/stable/c/0679c0c189d2548f00e1bac95be28e2df5c6c7f7
	https://git.kernel.org/stable/c/6e26a41c4c1a706edaaa7c7dffc6b3b945707a55
	https://git.kernel.org/stable/c/ee1d7274102285d78a53161fc705a8d8cd40b066