{"id":"CVE-2026-90342","summary":"bpf: Fix mmap_lock deadlock on arena lock failure","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix mmap_lock deadlock on arena lock failure\n\nReported by the Sashiko AI review.\n\narena_vm_fault() returns VM_FAULT_RETRY when it can't take\narena-\u003espinlock, but it never took mmap_lock. The fault path assumes a\nVM_FAULT_RETRY handler already dropped mmap_lock and re-takes it on the\nretry, so mmap_lock gets taken twice and can deadlock:\n\n\tdo_user_addr_fault()\n\t{\n\t\tfault = handle_mm_fault(...);   // calls arena_vm_fault()\n\t\tif (fault & VM_FAULT_RETRY)\n\t\t\tgoto retry;   // re-locks mmap_lock\n\t\tmmap_read_unlock(mm);\n\t}\n\nReturn VM_FAULT_SIGBUS instead, for two reasons:\n\n1. We could keep VM_FAULT_RETRY, but then we'd have to drop the fault\n   lock first and cap the retry ourselves, the way __folio_lock_or_retry()\n   does.\n\n2. A failed raw_res_spin_lock_irqsave() already means a possible deadlock\n   was detected, so retrying just hits the same lock again.\n\nSo returning VM_FAULT_RETRY here is overkill.","modified":"2026-09-18T03:48:37.791841513Z","published":"2026-09-17T16:08:53.010Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90342.json","cna_assigner":"Linux"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/0b10b945479c954393d62ee3229d2f224a4ca91c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/af8087f16714f7620c4db3e732baaa1b2337948f"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90342.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-90342"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"b8467290edab4bafae352bf3f317055669a1a458"},{"fixed":"af8087f16714f7620c4db3e732baaa1b2337948f"},{"fixed":"0b10b945479c954393d62ee3229d2f224a4ca91c"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90342.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"7.0.0"},{"fixed":"7.2.6"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90342.json"}}],"schema_version":"1.9.0"}