CVE-2025-39843
Description
In the Linux kernel, the following vulnerability has been resolved: mm: slub: avoid wake up kswapd in set_track_prepare set_track_prepare() can incur lock recursion. The issue is that it is called from hrtimer_start_range_ns holding the per_cpu(hrtimer_bases)[n].lock, but when enabled CONFIG_DEBUG_OBJECTS_TIMERS, may wake up kswapd in set_track_prepare, and try to hold the per_cpu(hrtimer_bases)[n].lock. Avoid deadlock caused by implicitly waking up kswapd by passing in allocation flags, which do not contain __GFP_KSWAPD_RECLAIM in the debug_objects_fill_pool() case. Inside stack depot they are processed by gfp_nested_mask(). Since ___slab_alloc() has preemption disabled, we mask out __GFP_DIRECT_RECLAIM from the flags there. The oops looks something like: BUG: spinlock recursion on CPU#3, swapper/3/0 lock: 0xffffff8a4bf29c80, .magic: dead4ead, .owner: swapper/3/0, .owner_cpu: 3 Hardware name: Qualcomm Technologies, Inc. Popsicle based on SM8850 (DT) Call trace: spin_bug+0x0 _raw_spin_lock_irqsave+0x80 hrtimer_try_to_cancel+0x94 task_contending+0x10c enqueue_dl_entity+0x2a4 dl_server_start+0x74 enqueue_task_fair+0x568 enqueue_task+0xac do_activate_task+0x14c ttwu_do_activate+0xcc try_to_wake_up+0x6c8 default_wake_function+0x20 autoremove_wake_function+0x1c __wake_up+0xac wakeup_kswapd+0x19c wake_all_kswapds+0x78 __alloc_pages_slowpath+0x1ac __alloc_pages_noprof+0x298 stack_depot_save_flags+0x6b0 stack_depot_save+0x14 set_track_prepare+0x5c ___slab_alloc+0xccc __kmalloc_cache_noprof+0x470 __set_page_owner+0x2bc post_alloc_hook[jt]+0x1b8 prep_new_page+0x28 get_page_from_freelist+0x1edc __alloc_pages_noprof+0x13c alloc_slab_page+0x244 allocate_slab+0x7c ___slab_alloc+0x8e8 kmem_cache_alloc_noprof+0x450 debug_objects_fill_pool+0x22c debug_object_activate+0x40 enqueue_hrtimer[jt]+0xdc hrtimer_start_range_ns+0x5f8 ...
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
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OS impact
| OS | Version | Status | Fixed in |
|---|---|---|---|
| rhel | 9 | fixed | |
| sles | affected | | |
| rocky | 9 | fixed | |
| debian | bookworm | fixed | 6.1.153-1 |
| debian | bullseye | fixed | 0 |
| debian | forky | fixed | 6.16.6-1 |
| debian | sid | fixed | 6.16.6-1 |
| debian | trixie | fixed | 6.12.48-1 |
| linux-kernel | affected | 6.1.151 | |
| linux-kernel | 6.17 | affected | |
| debian | 11.0 | affected | |
| almalinux | 9 | fixed | kernel-64k-devel-5.14.0-611.9.1.el9_7.aarch64.rpm |
References
- https://access.redhat.com/errata/RHSA-2025:21926
- https://git.kernel.org/stable/c/243b705a90ed8449f561a271cf251fd2e939f3db
- https://git.kernel.org/stable/c/522ffe298627cfe72539d72167c2e20e72b5e856
- https://git.kernel.org/stable/c/850470a8413a8a78e772c4f6bd9fe81ec6bd5b0f
- https://git.kernel.org/stable/c/994b03b9605d36d814c611385fbf90ca6db20aa8
- https://git.kernel.org/stable/c/eb3240ffd243bfb8b1e9dc568d484ecf9fd660ab
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
- https://cert-portal.siemens.com/productcert/html/ssa-032379.html
- https://www.suse.com/security/cve/CVE-2025-39843.html
- https://errata.rockylinux.org/RLSA-2025:21926
- https://security-tracker.debian.org/tracker/CVE-2025-39843
- https://bugzilla.redhat.com/2396941
- https://errata.almalinux.org/9/ALSA-2025-21926.html
CWEs
CWE-667
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.