CVE-2025-38327
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-07-10

Last updated on: 2025-11-18

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: fgraph: Do not enable function_graph tracer when setting funcgraph-args When setting the funcgraph-args option when function graph tracer is net enabled, it incorrectly enables it. Worse, it unregisters itself when it was never registered. Then when it gets enabled again, it will register itself a second time causing a WARNing. ~# echo 1 > /sys/kernel/tracing/options/funcgraph-args ~# head -20 /sys/kernel/tracing/trace # tracer: nop # # entries-in-buffer/entries-written: 813/26317372 #P:8 # # _-----=> irqs-off/BH-disabled # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / _-=> migrate-disable # |||| / delay # TASK-PID CPU# ||||| TIMESTAMP FUNCTION # | | | ||||| | | <idle>-0 [007] d..4. 358.966010: 7) 1.692 us | fetch_next_timer_interrupt(basej=4294981640, basem=357956000000, base_local=0xffff88823c3ae040, base_global=0xffff88823c3af300, tevt=0xffff888100e47cb8); <idle>-0 [007] d..4. 358.966012: 7) | tmigr_cpu_deactivate(nextexp=357988000000) { <idle>-0 [007] d..4. 358.966013: 7) | _raw_spin_lock(lock=0xffff88823c3b2320) { <idle>-0 [007] d..4. 358.966014: 7) 0.981 us | preempt_count_add(val=1); <idle>-0 [007] d..5. 358.966017: 7) 1.058 us | do_raw_spin_lock(lock=0xffff88823c3b2320); <idle>-0 [007] d..4. 358.966019: 7) 5.824 us | } <idle>-0 [007] d..5. 358.966021: 7) | tmigr_inactive_up(group=0xffff888100cb9000, child=0x0, data=0xffff888100e47bc0) { <idle>-0 [007] d..5. 358.966022: 7) | tmigr_update_events(group=0xffff888100cb9000, child=0x0, data=0xffff888100e47bc0) { Notice the "tracer: nop" at the top there. The current tracer is the "nop" tracer, but the content is obviously the function graph tracer. Enabling function graph tracing will cause it to register again and trigger a warning in the accounting: ~# echo function_graph > /sys/kernel/tracing/current_tracer -bash: echo: write error: Device or resource busy With the dmesg of: ------------[ cut here ]------------ WARNING: CPU: 7 PID: 1095 at kernel/trace/ftrace.c:3509 ftrace_startup_subops+0xc1e/0x1000 Modules linked in: kvm_intel kvm irqbypass CPU: 7 UID: 0 PID: 1095 Comm: bash Not tainted 6.16.0-rc2-test-00006-gea03de4105d3 #24 PREEMPT Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:ftrace_startup_subops+0xc1e/0x1000 Code: 48 b8 22 01 00 00 00 00 ad de 49 89 84 24 88 01 00 00 8b 44 24 08 89 04 24 e9 c3 f7 ff ff c7 04 24 ed ff ff ff e9 b7 f7 ff ff <0f> 0b c7 04 24 f0 ff ff ff e9 a9 f7 ff ff c7 04 24 f4 ff ff ff e9 RSP: 0018:ffff888133cff948 EFLAGS: 00010202 RAX: 0000000000000001 RBX: 1ffff1102679ff31 RCX: 0000000000000000 RDX: 1ffffffff0b27a60 RSI: ffffffff8593d2f0 RDI: ffffffff85941140 RBP: 00000000000c2041 R08: ffffffffffffffff R09: ffffed1020240221 R10: ffff88810120110f R11: ffffed1020240214 R12: ffffffff8593d2f0 R13: ffffffff8593d300 R14: ffffffff85941140 R15: ffffffff85631100 FS: 00007f7ec6f28740(0000) GS:ffff8882b5251000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f7ec6f181c0 CR3: 000000012f1d0005 CR4: 0000000000172ef0 Call Trace: <TASK> ? __pfx_ftrace_startup_subops+0x10/0x10 ? find_held_lock+0x2b/0x80 ? ftrace_stub_direct_tramp+0x10/0x10 ? ftrace_stub_direct_tramp+0x10/0x10 ? trace_preempt_on+0xd0/0x110 ? __pfx_trace_graph_entry_args+0x10/ ---truncated---
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Meta Information
Published
2025-07-10
Last Modified
2025-11-18
Generated
2026-05-07
AI Q&A
2025-07-10
EPSS Evaluated
2026-05-05
NVD
CVE-2025-38327
Affected Vendors & Products
Showing 3 associated CPEs
Vendor Product Version / Range
linux linux_kernel 6.16
linux linux_kernel 6.16
linux linux_kernel From 5.15.160 (inc) to 5.16 (inc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-NVD-CWE-noinfo
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability occurs in the Linux kernel's function graph tracer. When the funcgraph-args option is set without enabling the function graph tracer, the kernel incorrectly enables the tracer. Additionally, it unregisters itself even though it was never registered, and when enabled again, it registers twice, causing a warning and potential instability in the kernel tracing system.


How can this vulnerability impact me? :

The vulnerability can cause warnings and errors in the kernel tracing system, potentially leading to instability or unexpected behavior when using function graph tracing. This could affect system reliability or debugging processes that rely on kernel tracing.


How can this vulnerability be detected on my network or system? Can you suggest some commands?

This vulnerability can be detected by checking the state of the function graph tracer and the funcgraph-args option in the Linux kernel tracing subsystem. You can use the following commands to detect signs of the vulnerability: 1. Check if funcgraph-args is enabled: echo 1 > /sys/kernel/tracing/options/funcgraph-args 2. Inspect the trace buffer for inconsistencies or unexpected function graph tracer output while the current tracer is 'nop': head -20 /sys/kernel/tracing/trace 3. Attempt to enable the function graph tracer and observe if an error or warning occurs: echo function_graph > /sys/kernel/tracing/current_tracer If enabling the function graph tracer results in a "write error: Device or resource busy" or kernel warnings in dmesg related to ftrace_startup_subops, it indicates the presence of the vulnerability.


What immediate steps should I take to mitigate this vulnerability?

Immediate mitigation involves avoiding enabling the funcgraph-args option when the function graph tracer is not already enabled, as this triggers the vulnerability. Additionally, do not attempt to switch the current tracer to function_graph if the system reports it as busy or if warnings appear in dmesg. Applying the Linux kernel update or patch that resolves this issue is the definitive mitigation step.


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