CVE-2026-45914: Revert "hwmon: (ibmpex) fix use-after-free in high/low store"
In the Linux kernel, the following vulnerability has been resolved:
Revert "hwmon: (ibmpex) fix use-after-free in high/low store"
This reverts commit 6946c726c3f4c36f0f049e6f97e88c510b15f65d.
Jean Delvare points out that the patch does not completely fix the reported problem, that it in fact introduces a (new) race condition, and that it may actually not be needed in the first place.
Various AI reviews agree. Specific and relevant AI feedback:
" This reordering sets the driver data to NULL before removing the sensor attributes in the loop below.
ibmpexshowsensor() retrieves this driver data via devgetdrvdata() but does not check if it is NULL before dereferencing it to access data->sensors[].
If a userspace process reads a sensor file (like temp1input) while this delete function is running, could it race with the devsetdrvdata(..., NULL) call here and crash in ibmpexshowsensor()?
Would it be safer to keep the original order where deviceremovefile() is called before clearing the driver data? deviceremovefile() should wait for any active sysfs callbacks to complete, which might already prevent the use-after-free this patch intends to fix. "
Revert the offending patch. If it can be shown that the originally reported alleged race condition does indeed exist, it can always be re-introduced with a complete fix.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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ubuntu/linux-aws-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1060.63~22.04.1 - Upgrade
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ubuntu/linux-gcp-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1063.69~22.04.1 - Upgrade
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ubuntu/linux-azure-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1062.69+fips1 - Upgrade
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Linux kernelto a version that resolves this vulnerability.Patch 6946c726c3f4c36f0f049e6f97e88c510b15f65d
Event History
Frequently Asked Questions
Who is exposed to this issue?
Systems running the Linux kernel with the hwmon ibmpex driver are relevant. Exploitation requires local access and low privileges; the described race involves userspace reading an ibmpex sensor sysfs file while the driver delete path runs.
What does an attacker need to do to exploit the race?
A local low-privileged process would need to read a sensor attribute such as temp1_input concurrently with driver removal. The vulnerable ordering can set driver data to NULL before sensor attributes are removed, while ibmpex_show_sensor() dereferences that data without a NULL check.
How can I determine whether a system has the problematic change?
Check the kernel source or applied stable commits for the referenced revert commits: 05112ba67c824ab416cd54307c0b50aba9f0047a, efd68429f23fb4015b0ebc2392334059e06fad18, or f448acd86835a650f9ea83460b9ca347d3aafba5. A kernel containing the revert removes the offending patch described by this issue.