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Date: Fri,  5 Jul 2024 08:55:23 +0200
From: Greg Kroah-Hartman <>
Cc: Greg Kroah-Hartman <>
Subject: CVE-2024-39479: drm/i915/hwmon: Get rid of devm


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

drm/i915/hwmon: Get rid of devm

When both hwmon and hwmon drvdata (on which hwmon depends) are device
managed resources, the expectation, on device unbind, is that hwmon will be
released before drvdata. However, in i915 there are two separate code
paths, which both release either drvdata or hwmon and either can be
released before the other. These code paths (for device unbind) are as
follows (see also the bug referenced below):

Call Trace:
intel_pxp_tee_component_fini+0x29/0x40 [i915]
intel_pxp_fini+0x33/0x80 [i915]
i915_driver_remove+0x4c/0x120 [i915]
i915_pci_remove+0x19/0x30 [i915]


Call Trace:

This means that in i915, if use devm, we cannot gurantee that hwmon will
always be released before drvdata. Which means that we have a uaf if hwmon
sysfs is accessed when drvdata has been released but hwmon hasn't.

The only way out of this seems to be do get rid of devm_ and release/free
everything explicitly during device unbind.

v2: Change commit message and other minor code changes
v3: Cleanup from i915_hwmon_register on error (Armin Wolf)
v4: Eliminate potential static analyzer warning (Rodrigo)
    Eliminate fetch_and_zero (Jani)
v5: Restore previous logic for ddat_gt->hwmon_dev error return (Andi)

The Linux kernel CVE team has assigned CVE-2024-39479 to this issue.

Affected and fixed versions

	Fixed in 6.6.34 with commit cfa73607eb21
	Fixed in 6.9.5 with commit ce5a22d22db6
	Fixed in 6.10-rc1 with commit 5bc9de065b8b

Please see 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
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:


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:

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