tracing: Fix union collision of module and refcnt for dynamic events

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Summary

CVECVE-2026-68174
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-10 13:20:04 UTC
Updated2026-08-10 13:20:04 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: tracing: Fix union collision of module and refcnt for dynamic events In 'struct trace_event_call', the 'module' pointer and the 'refcnt' atomic variable share the same memory space in a union. For dynamic events, the union member is 'refcnt', which acts as an active reference counter. When a dynamic event (such as kprobe, uprobe, fprobe, eprobe, or wprobe) has a non-zero reference count (e.g. due to active event triggers or perf attachments), its 'call->module' evaluates to a small non-zero integer instead of NULL. When filtering or setting events for a specific module (e.g., writing ':mod:<module>' to 'set_event'), the code in '__ftrace_set_clr_event_nolock()' and 'update_event_fields()' reads 'call->module' directly without checking whether the event is dynamic. This causes the kernel to treat the small integer (refcnt) as a 'struct module' pointer, leading to a NULL/invalid pointer dereference (Oops) when dereferencing the module name. Fix this by ensuring that the 'TRACE_EVENT_FL_DYNAMIC' flag is checked before treating 'call->module' as a valid pointer in these code paths.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 4c86bc531e60900053384867c082675bba82c29f b6a4575f22925da7e6aa00171e9fc0e5029c0bc9 git Not specified
CNA Linux Linux affected 4c86bc531e60900053384867c082675bba82c29f 43a23dfe0024afd3d2b0232e987d0292919a9b24 git Not specified
CNA Linux Linux affected 4c86bc531e60900053384867c082675bba82c29f b4eb07bde606c2096b24252be589e735eff6d413 git Not specified
CNA Linux Linux affected 6.14 Not specified
CNA Linux Linux unaffected 6.14 semver Not specified
CNA Linux Linux unaffected 6.18.42 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.6 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2-rc5 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/43a23dfe0024afd3d2b0232e987d0292919a9b24 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b6a4575f22925da7e6aa00171e9fc0e5029c0bc9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b4eb07bde606c2096b24252be589e735eff6d413 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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