{"id":"CVE-2026-90046","state":"PUBLISHED","title":"mm/page_alloc: don't spin_trylock() in NMI on UP","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/page_alloc: don't spin_trylock() in NMI on UP\n\nPatch series \"mm/page_alloc: fixes for free_pages_nolock() on RT/UP\".\n\nPre-existing bugs found by Sashiko during review of this other series:\nhttps://lore.kernel.org/all/20260703-alloc-trylock-v5-0-c87b714e19d3@google.com/\n\nI have not reproduced these bugs, and I suspect there is no real-world\nuser that is affected by them.\n\n\nThis patch (of 2):\n\nAs noted in can_spin_trylock(), using this is unsafe in this context. \ncommit 620b46ed6ae17 (\"mm/page_alloc: return NULL early from\nalloc_frozen_pages_nolock() in NMI on UP\") fixed this on the alloc side\nbut missed the free side.\n\nImpact: If BPF programs using these features in NMI (probably tracing) are\npresent on non-SMP builds this might crash the kernel and is probably\nexploitable by local attackers for privilege escalation.","publishedAt":"2026-09-16T10:33:43.156Z","updatedAt":"2026-10-19T08:57:04.231Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"8c57b687e8331eb80e302a2c528b18b966a9ac7a","status":"affected","lessThan":"06c76d3c389ff504052f64b1acee44651bd847fa","versionType":"git"},{"version":"8c57b687e8331eb80e302a2c528b18b966a9ac7a","status":"affected","lessThan":"68a069b407303e71db371df85036101e8ff59280","versionType":"git"},{"version":"8c57b687e8331eb80e302a2c528b18b966a9ac7a","status":"affected","lessThan":"3105ae628fb785d48b49256468be4f21a7b3cfc0","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/page_alloc.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.15","versionType":"semver"},{"version":"6.18.51","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.5","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/page_alloc.c"]}],"references":["https://git.kernel.org/stable/c/06c76d3c389ff504052f64b1acee44651bd847fa","https://git.kernel.org/stable/c/68a069b407303e71db371df85036101e8ff59280","https://git.kernel.org/stable/c/3105ae628fb785d48b49256468be4f21a7b3cfc0"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:34.582Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/90xxx/CVE-2026-90046.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-90046","state":"PUBLISHED","datePublished":"2026-09-16T10:33:43.156Z","dateUpdated":"2026-10-19T08:57:04.231Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-11T19:38:34.783Z"},"containers":{"cna":{"title":"mm/page_alloc: don't spin_trylock() in NMI on UP","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/page_alloc: don't spin_trylock() in NMI on UP\n\nPatch series \"mm/page_alloc: fixes for free_pages_nolock() on RT/UP\".\n\nPre-existing bugs found by Sashiko during review of this other series:\nhttps://lore.kernel.org/all/20260703-alloc-trylock-v5-0-c87b714e19d3@google.com/\n\nI have not reproduced these bugs, and I suspect there is no real-world\nuser that is affected by them.\n\n\nThis patch (of 2):\n\nAs noted in can_spin_trylock(), using this is unsafe in this context. \ncommit 620b46ed6ae17 (\"mm/page_alloc: return NULL early from\nalloc_frozen_pages_nolock() in NMI on UP\") fixed this on the alloc side\nbut missed the free side.\n\nImpact: If BPF programs using these features in NMI (probably tracing) are\npresent on non-SMP builds this might crash the kernel and is probably\nexploitable by local attackers for privilege escalation."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"8c57b687e8331eb80e302a2c528b18b966a9ac7a","status":"affected","lessThan":"06c76d3c389ff504052f64b1acee44651bd847fa","versionType":"git"},{"version":"8c57b687e8331eb80e302a2c528b18b966a9ac7a","status":"affected","lessThan":"68a069b407303e71db371df85036101e8ff59280","versionType":"git"},{"version":"8c57b687e8331eb80e302a2c528b18b966a9ac7a","status":"affected","lessThan":"3105ae628fb785d48b49256468be4f21a7b3cfc0","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/page_alloc.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.15","versionType":"semver"},{"version":"6.18.51","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.5","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/page_alloc.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/06c76d3c389ff504052f64b1acee44651bd847fa"},{"url":"https://git.kernel.org/stable/c/68a069b407303e71db371df85036101e8ff59280"},{"url":"https://git.kernel.org/stable/c/3105ae628fb785d48b49256468be4f21a7b3cfc0"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - free_pages_nolock is reached from local BPF programs (arena/bpf_map_alloc_pages and related nolock helpers) running in NMI, typically a BPF_PROG_TYPE_PERF_EVENT overflow handler installed via bpf()/perf_event_open. It is not reachable from unauthenticated network packets or in-kernel servers such as ksmbd/nfsd.\nAC:L - Scoring assumes a uniprocessor (!CONFIG_SMP) kernel, a reasonable embedded/IoT deployment. An attacker who can attach a BPF perf-event program controls the NMI that calls free_pages_nolock and can concurrently run page-allocator work so the NMI interrupts zone->lock; the in-tree slub_kunit NMI overflow test shows this reentry is reliably triggerable.\nPR:L - Loading the NMI BPF program requires CAP_BPF and CAP_PERFMON, which are sub-root capabilities. BPF tokens can delegate those checks into a non-init user namespace in plausible container/tracing deployments, so this is treated as low privileges rather than init-namespace root.\nUI:N - The attacker loads the BPF program, programs the PMU, and drives local memory activity themselves. No separate victim action such as mounting a filesystem or opening a crafted file is required.\nS:U - Re-entrant buddy/zone-lock corruption stays inside the kernel's own security authority and yields local privilege escalation, not a VM, IOMMU, or other cross-boundary escape.\nC:H - Nested spin_trylock of zone->lock on UP lets the NMI mutate buddy freelists while the interrupted context is mid-update, corrupting page-allocator metadata. That overlapping-page primitive can be leveraged for arbitrary kernel memory disclosure.\nI:H - The same freelist corruption is a well-known arbitrary-write and control-flow hijack primitive, and the fix commit states the bug is probably exploitable by local attackers for privilege escalation.\nA:H - Re-entrant zone-lock and buddy updates crash the kernel via oops, panic, or a DEBUG_SPINLOCK BUG on UP, which is a full availability loss."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T08:57:04.231Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.15","versionEndExcluding":"6.18.51"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.15","versionEndExcluding":"7.2.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.15","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}