{"id":"CVE-2026-89991","revision":"2f5ca4ad37aa42bfb32cea322f23f340","records":[{"revision":"2f5ca4ad37aa42bfb32cea322f23f340","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-89991","aliases":[],"title":"bpf: Fix infinite loop in pcpu_freelist push with one possible CPU","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix infinite loop in pcpu_freelist push with one possible CPU\n\n__pcpu_freelist_push() can loop forever when only one CPU is possible\nand an NMI re-enters pcpu_freelist_push() while the interrupted context\nholds that CPU's freelist lock.\n\nAfter the current-CPU fast path fails, the fallback loop walks\ncpu_possible_mask while skipping the current CPU. With CONFIG_SMP=n, or\nwhen an SMP kernel is limited to one possible CPU with nr_cpus=1 or\npossible_cpus=1, there are no other possible CPUs to examine. The loop\ntherefore makes no lock acquisition attempt and can never make progress.\n\nThe following stack was observed on a UP system:\n\n  NMI context:\n    pcpu_freelist_push\n    free_htab_elem\n    htab_map_delete_elem\n    [perf-event BPF program]\n    __perf_event_overflow\n    perf_event_nmi_handler\n    exc_nmi\n\n  Interrupted context:\n    __pcpu_freelist_push\n    pcpu_freelist_push\n    free_htab_elem\n    htab_map_delete_elem\n    [raw_tp/sys_enter BPF program]\n    __bpf_trace_sys_enter\n    do_syscall_64\n\nraw_res_spin_lock() detects the same-CPU recursive acquisition and\nreturns -EDEADLK, but the subsequent fallback loop has no candidate head\non a system with one possible CPU.\n\nRestore the extra fallback head that existed before the rqspinlock\nconversion. Keep the current-CPU fast path, then try the other possible\nCPUs and finally the extra head. The additional head lets a push, which\ncannot fail without losing a preallocated element, make progress when the\nonly per-CPU head is held by the interrupted context.\n\nAlso check the extra head from the pop path so that nodes placed there\ncan be reused.","state":0,"publishedAt":"2026-09-16T10:33:05.097+00:00","modifiedAt":"2026-10-19T08:56:05.536+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                        \"kernel/bpf/percpu_freelist.c\",\n                        \"kernel/bpf/percpu_freelist.h\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"f2ac0e5d1c4dcc55d6510dcaefb8f45661a9a1fb\",\n                            \"lessThan\": \"a24a146ae2cb5d9faeea96d10010fcb6579abe1f\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"f2ac0e5d1c4dcc55d6510dcaefb8f45661a9a1fb\",\n                            \"lessThan\": \"a5b5e62baceff9e252c6535cf42a027d04f226cf\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"f2ac0e5d1c4dcc55d6510dcaefb8f45661a9a1fb\",\n                            \"lessThan\": \"efebf6496685c93150df5bb0794363ae70c5f58a\",\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\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"kernel/bpf/percpu_freelist.c\",\n                        \"kernel/bpf/percpu_freelist.h\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"6.15\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"6.15\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.51\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2.5\",\n                            \"lessThanOrEqual\": \"7.2.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.3\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[],"references":["https://git.kernel.org/stable/c/a24a146ae2cb5d9faeea96d10010fcb6579abe1f","https://git.kernel.org/stable/c/a5b5e62baceff9e252c6535cf42a027d04f226cf","https://git.kernel.org/stable/c/efebf6496685c93150df5bb0794363ae70c5f58a"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-89991","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-89991","identifiers":["CVE-2026-89991"]},"retained":false,"historicalAffected":[]}],"coverage":[]}