Bug 2395808 (CVE-2025-39829)

Summary: CVE-2025-39829 kernel: trace/fgraph: Fix the warning caused by missing unregister notifier
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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Description OSIDB Bzimport 2025-09-16 14:03:57 UTC 
In the Linux kernel, the following vulnerability has been resolved:

trace/fgraph: Fix the warning caused by missing unregister notifier

This warning was triggered during testing on v6.16:

notifier callback ftrace_suspend_notifier_call already registered
WARNING: CPU: 2 PID: 86 at kernel/notifier.c:23 notifier_chain_register+0x44/0xb0
...
Call Trace:
 <TASK>
 blocking_notifier_chain_register+0x34/0x60
 register_ftrace_graph+0x330/0x410
 ftrace_profile_write+0x1e9/0x340
 vfs_write+0xf8/0x420
 ? filp_flush+0x8a/0xa0
 ? filp_close+0x1f/0x30
 ? do_dup2+0xaf/0x160
 ksys_write+0x65/0xe0
 do_syscall_64+0xa4/0x260
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

When writing to the function_profile_enabled interface, the notifier was
not unregistered after start_graph_tracing failed, causing a warning the
next time function_profile_enabled was written.

Fixed by adding unregister_pm_notifier in the exception path.
Comment 1 Keith Grant 2025-09-16 16:39:55 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025091617-CVE-2025-39829-2ef1@gregkh/T