CVE-2024-27006: thermal/debugfs: Add missing count increment to thermal_debug_tz_trip_up()
In the Linux kernel, the following vulnerability has been resolved:
thermal/debugfs: Add missing count increment to thermal_debug_tz_trip_up()
The count field in struct trip_stats, representing the number of times
the zone temperature was above the trip point, needs to be incremented
in thermal_debug_tz_trip_up(), for two reasons.
First, if a trip point is crossed on the way up for the first time,
thermal_debug_update_temp() called from update_temperature() does
not see it because it has not been added to trips_crossed[] array
in the thermal zone's struct tz_debugfs object yet. Therefore, when
thermal_debug_tz_trip_up() is called after that, the trip point's
count value is 0, and the attempt to divide by it during the average
temperature computation leads to a divide error which causes the kernel
to crash. Setting the count to 1 before the division by incrementing it
fixes this problem.
Second, if a trip point is crossed on the way up, but it has been
crossed on the way up already before, its count value needs to be
incremented to make a record of the fact that the zone temperature is
above the trip now. Without doing that, if the mitigations applied
after crossing the trip cause the zone temperature to drop below its
threshold, the count will not be updated for this episode at all and
the average temperature in the trip statistics record will be somewhat
higher than it should be.
Cc :6.8+ <stable@vger.kernel.org> # 6.8+
Security readout for executives and security teams
Plain-English summary
CVE-2024-27006 is a Linux kernel bug in thermal debug statistics that can crash the kernel during a temperature trip-point update. The business impact is availability: affected systems may reboot or become unavailable if the vulnerable path is reached. The source bundle does not show active exploitation or a CVSS score.
Executive priority
Treat this as a moderate availability risk for affected Linux fleets. Prioritize patching servers where kernel crashes would disrupt production, but the supplied evidence does not justify emergency incident response based on exploitation.
Technical view
The issue is in thermal/debugfs. A missing increment of trip_stats.count can leave count at zero before average-temperature calculation, causing a divide error and kernel crash. The kernel fix increments the count in thermal_debug_tz_trip_up(). Sources identify Linux 6.8+ as affected and reference stable fixes plus Fedora kernel advisories.
Likely exposure
Exposure is most relevant to systems running affected Linux kernel 6.8-era builds, including 6.8, 6.8.8, and 6.9 as listed. Downstream exposure depends on whether the distribution kernel already includes the referenced stable commits or vendor updates.
Exploitation context
The provided sources describe a kernel crash condition, but do not provide evidence of active exploitation. CISA KEV status is false in the source bundle. No public exploit status, attacker prerequisites, or remote attack path is established by the supplied evidence.
Researcher notes
The root cause is a state-accounting bug in thermal_debug_tz_trip_up(): count was not incremented before use in average-temperature computation. Evidence is strong for crash impact and fix direction, but incomplete for exploitability, privilege requirements, and downstream package boundaries.
Mitigation direction
Update affected Linux kernels to vendor builds containing the referenced stable fixes.
Review Fedora advisories if running Fedora and apply the relevant kernel update.
For other distributions, check vendor guidance for fixed package versions.
If updates are delayed, document residual availability risk until vendor guidance is applied.
Validation and detection
Inventory hosts running Linux kernel 6.8-era versions listed as affected.
Confirm installed kernel packages include the referenced stable fix or downstream vendor backport.
Check Fedora systems against the cited Fedora package announcements.
Track reboot requirements after kernel update and confirm systems run the updated kernel.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Potential ATT&CK relevance
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CVE-2024-27006 mapping review
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