UBUNTU-CVE-2026-74636: Medium severity ubuntu/linux-hwe-edge vulnerability
In the Linux kernel, the following vulnerability has been resolved: tracing: Fix race between updateeventfields and, eventdefinefields The following sequence may leads race between eventdefinefields() and updateeventfields(): CPU0 (loads module A) CPU1 (loads module B) =============================== =============================== loadmodule(A) loadmodule(B) notifiercallchain notifiercallchain tracemodulenotify tracemodulenotify mutexlock(&eventmutex) traceeventupdateall() tracemoduleaddevents(A) downwrite(&traceeventsem) registerevent(callA) addeventtotracers(callA) eventdefinefields(callA) for each f: listforeachentry(field, listadd(&f->link, &class->fields, link) &class->fields) field = class->fields->next; Where access to the class->fields is not protected by the eventmutex in traceeventupdateall(). This produces the following panic: Unable to handle kernel access ... at virtual address 0000000000000018 pc : updateeventfields+0xf8/0x368 Call trace: updateeventfields+0xf8/0x368 traceeventupdateall+0x7c/0x2b4 tracemodulenotify+0x4c/0x1dc notifiercallchain+0x84/0x168 blockingnotifiercallchainrobust+0x64/0xd4 loadmodule+0x10c8/0x123c arm64sysfinitmodule+0x230/0x31c Fix by taking eventmutex in traceeventupdateall() before traceeventsem.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
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ubuntu/linux-aws-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1117.124~20.04.1 - Upgrade
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ubuntu/linux-azure-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1123.132~20.04.1 - Upgrade
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ubuntu/linux-azure-fde-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1122.131~20.04.1 - Upgrade
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ubuntu/linux-gcp-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1118.128~20.04.1 - Upgrade
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ubuntu/linux-hwe-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-198.208~20.04.1 - Upgrade
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ubuntu/linux-ibm-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1111.115~20.04.1 - Upgrade
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ubuntu/linux-intel-iotg-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1112.118~20.04.1 - Upgrade
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ubuntu/linux-lowlatency-hwe-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-195.205~20.04.1 - Upgrade
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ubuntu/linux-oracle-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1114.120~20.04.1 - Upgrade
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ubuntu/linux-riscv-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1111.115~20.04.1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 5.15.0-198.208 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 5.15.0-1117.124 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 5.15.0-1123.132 - Upgrade
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ubuntu/linux-azure-fdeto a version that resolves this vulnerability.Fixed in 5.15.0-1122.131 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 5.15.0-1118.128 - Upgrade
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ubuntu/linux-gketo a version that resolves this vulnerability.Fixed in 5.15.0-1113.119 - Upgrade
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ubuntu/linux-gkeopto a version that resolves this vulnerability.Fixed in 5.15.0-1100.108 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 5.15.0-1111.115 - Upgrade
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ubuntu/linux-intel-iotgto a version that resolves this vulnerability.Fixed in 5.15.0-1112.118 - Upgrade
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ubuntu/linux-kvmto a version that resolves this vulnerability.Fixed in 5.15.0-1109.114 - Upgrade
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ubuntu/linux-lowlatencyto a version that resolves this vulnerability.Fixed in 5.15.0-195.205 - Upgrade
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ubuntu/linux-nvidiato a version that resolves this vulnerability.Fixed in 5.15.0-1112.113 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 5.15.0-1114.120 - Upgrade
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ubuntu/linux-xilinx-zynqmpto a version that resolves this vulnerability.Fixed in 5.15.0-1080.84 - Upgrade
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ubuntu/linux-bluefieldto a version that resolves this vulnerability.Fixed in 5.15.0-1101.103 - Upgrade
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ubuntu/linux-intel-iot-realtimeto a version that resolves this vulnerability.Fixed in 5.15.0-1109.111 - Upgrade
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ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 5.15.0-1116.125 - Upgrade
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ubuntu/linux-aws-fipsto a version that resolves this vulnerability.Fixed in 5.15.0-1117.124+fips1 - Upgrade
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ubuntu/linux-azure-fipsto a version that resolves this vulnerability.Fixed in 5.15.0-1123.132+fips1 - Upgrade
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ubuntu/linux-fipsto a version that resolves this vulnerability.Fixed in 5.15.0-198.208+fips1 - Upgrade
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ubuntu/linux-gcp-fipsto a version that resolves this vulnerability.Fixed in 5.15.0-1118.128+fips1 - Compensating control
Modify the Linux kernel tracing code so trace_event_update_all() takes event_mutex before acquiring trace_event_sem, protecting access to class->fields.
Event History
Frequently Asked Questions
Which systems are exposed to this race condition?
The issue applies to the listed Ubuntu kernel packages: linux, linux-realtime, linux-azure, linux-gcp, linux-azure-fde, linux-gke, linux-riscv, and linux-gkeop. The race occurs during concurrent module loading involving trace-event field registration.
What conditions trigger the failure?
Two CPUs can load separate modules concurrently while one path updates trace-event fields and another defines event fields. Unprotected access to a trace event class's fields list can then cause a kernel access fault in update_event_fields().