CVE-2026-99247
Received Received - Intake

NULL Pointer Dereference in Linux Kernel Tracing Subsystem

Publication date: 2026-11-03

Last updated on: 2026-11-03

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: tracing: Do not initialize tracefs work if tracing is disabled If trace buffer allocation fails during early boot (e.g. in early_trace_init() -> allocate_trace_buffers()), tracing_disabled is left set to 1 and the global trace array events list remains uninitialized. Later during boot, tracer_init_tracefs() (invoked via fs_initcall) queues tracerfs_init_work asynchronously without checking if tracing was disabled. When tracer_init_tracefs_work_func() runs, it calls event_trace_init() and init_tracer_tracefs(&global_trace, NULL) unconditionally. This leads to __find_event_file() dereferencing an uninitialized tr->events list, causing an early boot NULL pointer dereference Oops: BUG: Kernel NULL pointer dereference on read at 0x00000010 Faulting instruction address: 0xc000000000485be0 Oops: Kernel access of bad area, sig: 7 [#1] ... NIP [c000000000485be0] __find_event_file+0x70/0x3c0 LR [c000000000448874] init_tracer_tracefs+0x274/0xc80 Call Trace: init_tracer_tracefs+0x274/0xc80 tracer_init_tracefs_work_func+0x50/0x320 process_one_work+0x1e8/0x5c0 worker_thread+0x1dc/0x3d0 kthread+0x194/0x1b0 start_kernel_thread+0x14/0x18 Check tracing_disabled at the beginning of tracer_init_tracefs_work_func() and return immediately if tracing is disabled or failed to initialize, preventing the crash.

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Meta Information

Published
2026-11-03
Last Modified
2026-11-03
Generated
2026-11-03
AI Q&A
2026-11-03
EPSS Evaluated
N/A
NVD
CVE-2026-99247
EUVD
EUVD-2026-115777

Affected Vendors & Products

Showing 7 associated CPEs
Vendor Product Version / Range
Linux Linux 6621a7004684bfcff5af4c8e4d37989941f42a6b
Linux Linux 6621a7004684bfcff5af4c8e4d37989941f42a6b
Linux Linux 6621a7004684bfcff5af4c8e4d37989941f42a6b
Linux Linux 6621a7004684bfcff5af4c8e4d37989941f42a6b
Linux Linux 6621a7004684bfcff5af4c8e4d37989941f42a6b
Linux Linux 6621a7004684bfcff5af4c8e4d37989941f42a6b
Linux Linux 5.19

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a Linux kernel vulnerability where a NULL pointer dereference occurs during early boot if trace buffer allocation fails. The issue arises because tracing_disabled remains set to 1 after a failure, but later code attempts to initialize tracefs without checking this flag, leading to a crash when accessing an uninitialized list.

Detection Guidance

This vulnerability is specific to the Linux kernel and manifests during early boot if trace buffer allocation fails. Detection requires checking kernel logs for early boot errors or NULL pointer dereference messages during system startup.

Impact Analysis

This vulnerability causes a kernel crash during system boot if trace buffer allocation fails. The result is a system failure to start properly, leading to unbootable systems or repeated crashes until the issue is resolved.

Mitigation Strategies

Apply the latest kernel patch that resolves this issue. Ensure your system is updated to a version where the fix for tracing initialization is included. Monitor kernel logs for trace-related errors during boot.

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