{"id":"CVE-2026-99093","revision":"f35bfc5852394832bbfbb0a135355e36","records":[{"revision":"f35bfc5852394832bbfbb0a135355e36","observedAt":"2026-10-26T15:35:30.984+00:00","statement":{"source":"cve-program","id":"CVE-2026-99093","aliases":[],"title":"mm: don't schedule deferred kernel page table freeing while booting","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm: don't schedule deferred kernel page table freeing while booting\n\nBooting with a boot-time function tracer and a filter, for example\n\n  ftrace=function ftrace_filter=pud_free_pmd_page\n\npanics on 7.3-rc4 as soon as the tracer starts:\n\n  [   23.531178] Starting tracer 'function'\n  [   23.675800] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000038: 0000 [#1] SMP KASAN NOPTI\n  [   23.819917] KASAN: null-ptr-deref in range [0x00000000000001c0-0x00000000000001c7]\n  [   23.964025] CPU: 0 UID: 0 PID: 0 Comm: swapper Not tainted 7.3.0-rc4-fe2ec83746e5-with-fixes-v2+ #195 PREEMPT(undef)\n  [   24.252248] RIP: 0010:__queue_work+0xab/0xf00\n  [   25.981629] Call Trace:\n  [   26.125727]  <TASK>\n  [   26.413912]  ? pagetable_free_kernel+0x20/0x120\n  [   26.990283]  queue_work_on+0x97/0xf0\n  [   27.134382]  __cpa_collapse_large_pages+0x501/0x6f0\n  [   27.566662]  cpa_flush+0x394/0x620\n  [   27.998953]  change_page_attr_set_clr+0x321/0x4a0\n  [   29.151729]  set_memory_rox+0xa2/0xf0\n  [   29.584018]  create_trampoline+0x431/0x6f0\n  ...\n  [   44.343347] Kernel panic - not syncing: Attempted to kill the idle task!\n\nThe boot-time tracer is started from early_trace_init(), which runs\nbefore workqueue_init_early().  Making its trampoline read-only splits a\nlarge page, and CPA collapses it again right away.  The split table has\nbeen a kernel page table since commit 9e4a3ec3411b\n(\"x86/mm/pat: Allocate split page tables as kernel page tables\"), so the\ncollapse frees it through pagetable_free_kernel(), which queues work on\nsystem_percpu_wq - still NULL at that point.  That commit is correct in\nitself; it only lets CPA reach pagetable_free_kernel() before the\nworkqueue that function relies on exists.\n\nKeep putting the table on the list, but don't schedule the work while\nthe system is still booting.  A core_initcall schedules it once to free\nwhatever was queued by then.","state":0,"publishedAt":"2026-10-26T14:52:01.45+00:00","modifiedAt":"2026-10-26T14:52:01.45+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"mm/pgtable-generic.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"84e0cd79d57f06b872154eb5d8f610584133f260\",\n                            \"lessThan\": \"7a25ca170c12a9328f6fcf4410713beb516b01c0\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"922873cf4fc34124215070a8ad391bf831538bb9\",\n                            \"lessThan\": \"df6c704a08bc0925d5db047b0a6221f962bda4d9\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"9e4a3ec3411bb6bb59e3c1f29b75609f1e87aac4\",\n                            \"lessThan\": \"2fb552b0bee70c24c092720028ab4620f5eb2646\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"mm/pgtable-generic.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"6.18.53\",\n                            \"lessThan\": \"6.18.57\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2.7\",\n                            \"lessThan\": \"7.2.11\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        }\n                    ]\n                }"}],"metrics":[],"references":["https://git.kernel.org/stable/c/7a25ca170c12a9328f6fcf4410713beb516b01c0","https://git.kernel.org/stable/c/df6c704a08bc0925d5db047b0a6221f962bda4d9","https://git.kernel.org/stable/c/2fb552b0bee70c24c092720028ab4620f5eb2646"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-99093","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-99093","identifiers":["CVE-2026-99093"]},"retained":false,"historicalAffected":[]}],"coverage":[]}