CVE-2026-99093
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.
Executive briefing
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Evidence confidence: Not assessed Evidence-derived, not an exploitability verdict
Severity & attack characteristics
CVSS vector:Not supplied
No CVSS vector is currently available in the source record.
Technical explanation & impact
Technical root-cause details are not available in the current source record.
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Affected products and versions
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Remediation & validation
- Identify exposure by comparing the affected product and version ranges with your asset inventory, SBOM and externally exposed services.
- Review the linked vendor security advisory or patch notes. Upgrade to a vendor-confirmed fixed release; do not infer a fixed version from the CVE description.
- Until patched, consider restricting network access or disabling the affected feature where operationally safe. These are temporary controls, not a substitute for a vendor fix.
- Validate the remediation with a version check and vulnerability rescan, then retain change evidence.
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Vendor advisories, patches & exploit references
No external references are currently supplied in the CVE record.