mm: don't schedule deferred kernel page table freeing while booting
Summary
| CVE | CVE-2026-99093 |
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| State | PUBLISHED |
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| Assigner | Linux |
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| Source Priority | CVE Program / NVD first with legacy fallback |
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| Published | 2026-10-26 15:16:48 UTC |
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| Updated | 2026-10-26 15:16:48 UTC |
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| Description | In the Linux kernel, the following vulnerability has been resolved:
mm: don't schedule deferred kernel page table freeing while booting
Booting with a boot-time function tracer and a filter, for example
ftrace=function ftrace_filter=pud_free_pmd_page
panics on 7.3-rc4 as soon as the tracer starts:
[ 23.531178] Starting tracer 'function'
[ 23.675800] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000038: 0000 [#1] SMP KASAN NOPTI
[ 23.819917] KASAN: null-ptr-deref in range [0x00000000000001c0-0x00000000000001c7]
[ 23.964025] CPU: 0 UID: 0 PID: 0 Comm: swapper Not tainted 7.3.0-rc4-fe2ec83746e5-with-fixes-v2+ #195 PREEMPT(undef)
[ 24.252248] RIP: 0010:__queue_work+0xab/0xf00
[ 25.981629] Call Trace:
[ 26.125727] <TASK>
[ 26.413912] ? pagetable_free_kernel+0x20/0x120
[ 26.990283] queue_work_on+0x97/0xf0
[ 27.134382] __cpa_collapse_large_pages+0x501/0x6f0
[ 27.566662] cpa_flush+0x394/0x620
[ 27.998953] change_page_attr_set_clr+0x321/0x4a0
[ 29.151729] set_memory_rox+0xa2/0xf0
[ 29.584018] create_trampoline+0x431/0x6f0
...
[ 44.343347] Kernel panic - not syncing: Attempted to kill the idle task!
The boot-time tracer is started from early_trace_init(), which runs
before workqueue_init_early(). Making its trampoline read-only splits a
large page, and CPA collapses it again right away. The split table has
been a kernel page table since commit 9e4a3ec3411b
("x86/mm/pat: Allocate split page tables as kernel page tables"), so the
collapse frees it through pagetable_free_kernel(), which queues work on
system_percpu_wq - still NULL at that point. That commit is correct in
itself; it only lets CPA reach pagetable_free_kernel() before the
workqueue that function relies on exists.
Keep putting the table on the list, but don't schedule the work while
the system is still booting. A core_initcall schedules it once to free
whatever was queued by then. |
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Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
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| CNA |
Linux |
Linux |
affected 84e0cd79d57f06b872154eb5d8f610584133f260 7a25ca170c12a9328f6fcf4410713beb516b01c0 git |
Not specified |
| CNA |
Linux |
Linux |
affected 922873cf4fc34124215070a8ad391bf831538bb9 df6c704a08bc0925d5db047b0a6221f962bda4d9 git |
Not specified |
| CNA |
Linux |
Linux |
affected 9e4a3ec3411bb6bb59e3c1f29b75609f1e87aac4 2fb552b0bee70c24c092720028ab4620f5eb2646 git |
Not specified |
| CNA |
Linux |
Linux |
affected 6.18.53 6.18.57 semver |
Not specified |
| CNA |
Linux |
Linux |
affected 7.2.7 7.2.11 semver |
Not specified |
References
| Reference | Source | Link | Tags |
|---|
| git.kernel.org/stable/c/2fb552b0bee70c24c092720028ab4620f5eb2646 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/df6c704a08bc0925d5db047b0a6221f962bda4d9 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/7a25ca170c12a9328f6fcf4410713beb516b01c0 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| CVE Program record |
CVE.ORG |
www.cve.org |
canonical |
| NVD vulnerability detail |
NVD |
nvd.nist.gov |
canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.