{"resultsPerPage":1,"startIndex":0,"totalResults":1,"format":"NVD_CVE","version":"2.0","timestamp":"2026-05-04T00:43:00.522","vulnerabilities":[{"cve":{"id":"CVE-2025-37964","sourceIdentifier":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","published":"2025-05-20T16:15:34.683","lastModified":"2025-12-16T20:30:11.323","vulnStatus":"Analyzed","cveTags":[],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nx86/mm: Eliminate window where TLB flushes may be inadvertently skipped\n\ntl;dr: There is a window in the mm switching code where the new CR3 is\nset and the CPU should be getting TLB flushes for the new mm.  But\nshould_flush_tlb() has a bug and suppresses the flush.  Fix it by\nwidening the window where should_flush_tlb() sends an IPI.\n\nLong Version:\n\n=== History ===\n\nThere were a few things leading up to this.\n\nFirst, updating mm_cpumask() was observed to be too expensive, so it was\nmade lazier.  But being lazy caused too many unnecessary IPIs to CPUs\ndue to the now-lazy mm_cpumask().  So code was added to cull\nmm_cpumask() periodically[2].  But that culling was a bit too aggressive\nand skipped sending TLB flushes to CPUs that need them.  So here we are\nagain.\n\n=== Problem ===\n\nThe too-aggressive code in should_flush_tlb() strikes in this window:\n\n\t// Turn on IPIs for this CPU/mm combination, but only\n\t// if should_flush_tlb() agrees:\n\tcpumask_set_cpu(cpu, mm_cpumask(next));\n\n\tnext_tlb_gen = atomic64_read(&next->context.tlb_gen);\n\tchoose_new_asid(next, next_tlb_gen, &new_asid, &need_flush);\n\tload_new_mm_cr3(need_flush);\n\t// ^ After 'need_flush' is set to false, IPIs *MUST*\n\t// be sent to this CPU and not be ignored.\n\n        this_cpu_write(cpu_tlbstate.loaded_mm, next);\n\t// ^ Not until this point does should_flush_tlb()\n\t// become true!\n\nshould_flush_tlb() will suppress TLB flushes between load_new_mm_cr3()\nand writing to 'loaded_mm', which is a window where they should not be\nsuppressed.  Whoops.\n\n=== Solution ===\n\nThankfully, the fuzzy \"just about to write CR3\" window is already marked\nwith loaded_mm==LOADED_MM_SWITCHING.  Simply checking for that state in\nshould_flush_tlb() is sufficient to ensure that the CPU is targeted with\nan IPI.\n\nThis will cause more TLB flush IPIs.  But the window is relatively small\nand I do not expect this to cause any kind of measurable performance\nimpact.\n\nUpdate the comment where LOADED_MM_SWITCHING is written since it grew\nyet another user.\n\nPeter Z also raised a concern that should_flush_tlb() might not observe\n'loaded_mm' and 'is_lazy' in the same order that switch_mm_irqs_off()\nwrites them.  Add a barrier to ensure that they are observed in the\norder they are written."},{"lang":"es","value":"En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: x86/mm: Eliminar la ventana donde los vaciados de TLB pueden omitirse inadvertidamente tl;dr: Hay una ventana en el código de conmutación mm donde se establece el nuevo CR3 y la CPU debería obtener vaciados de TLB para el nuevo mm. Pero should_flush_tlb() tiene un error y suprime el vaciado. Arréglelo ampliando la ventana donde should_flush_tlb() envía una IPI. Versión larga: === Historial === Hubo algunas cosas que llevaron a esto. Primero, se observó que actualizar mm_cpumask() era demasiado costoso, por lo que se hizo más perezoso. Pero ser perezoso causó demasiados IPI innecesarios a las CPU debido al ahora perezoso mm_cpumask(). Entonces se agregó código para descartar mm_cpumask() periódicamente[2]. Pero ese descarte fue demasiado agresivo y omitió el envío de vaciados de TLB a las CPU que los necesitan. Así que aquí estamos de nuevo. === Problema === El código demasiado agresivo en should_flush_tlb() ataca en esta ventana: // Activa las IPI para esta combinación de CPU/mm, pero solo si should_flush_tlb() está de acuerdo: cpumask_set_cpu(cpu, mm_cpumask(next)); next_tlb_gen = atomic64_read(&next->context.tlb_gen); choose_new_asid(next, next_tlb_gen, &new_asid, &need_flush); load_new_mm_cr3(need_flush); // ^ Después de que 'need_flush' se establece en falso, las IPI *DEBEN* // enviarse a esta CPU y no ignorarse. this_cpu_write(cpu_tlbstate.loaded_mm, next); // ^ ¡No es hasta este punto que should_flush_tlb() // se vuelve verdadero! should_flush_tlb() suprimirá los vaciados de TLB entre load_new_mm_cr3() y la escritura en 'loaded_mm', que es una ventana donde no deberían suprimirse. ¡Uy! === Solución === Afortunadamente, la ventana difusa \"a punto de escribir CR3\" ya está marcada con load_mm==LOADED_MM_SWITCHING. Simplemente comprobar ese estado en should_flush_tlb() es suficiente para asegurar que la CPU esté dirigida a un IPI. Esto provocará más IPI de vaciado de TLB. Sin embargo, la ventana es relativamente pequeña y no preveo que esto tenga ningún impacto medible en el rendimiento. Actualice el comentario donde se escribe LOADED_MM_SWITCHING, ya que ha generado otro usuario. Peter Z también planteó la preocupación de que should_flush_tlb() podría no observar 'loaded_mm' e 'is_lazy' en el mismo orden en que switch_mm_irqs_off() los escribe. Añade una barrera para garantizar que se observen en el orden en que están escritos."}],"metrics":{"cvssMetricV31":[{"source":"nvd@nist.gov","type":"Primary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","baseScore":5.5,"baseSeverity":"MEDIUM","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":3.6}]},"weaknesses":[{"source":"nvd@nist.gov","type":"Primary","description":[{"lang":"en","value":"NVD-CWE-noinfo"}]}],"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15.179","versionEndExcluding":"5.15.183","matchCriteriaId":"D2AFD248-20FC-485D-A1CC-13D0E8DCC81A"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1.129","versionEndExcluding":"6.1.139","matchCriteriaId":"4C6814B6-DBF3-43D3-8C83-AB2A7B017FC6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6.79","versionEndExcluding":"6.6.91","matchCriteriaId":"7CC8774F-8BD4-4950-8F1C-0AD7E981084D"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12.16","versionEndExcluding":"6.12.29","matchCriteriaId":"AC82108A-29E5-4E88-93EC-856824C6788E"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.13.4","versionEndExcluding":"6.14.7","matchCriteriaId":"8869956D-8A8C-40D1-91E5-1709F4A31C01"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.15:rc1:*:*:*:*:*:*","matchCriteriaId":"8D465631-2980-487A-8E65-40AE2B9F8ED1"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.15:rc2:*:*:*:*:*:*","matchCriteriaId":"4C9D071F-B28E-46EC-AC61-22B913390211"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.15:rc3:*:*:*:*:*:*","matchCriteriaId":"13FC0DDE-E513-465E-9E81-515702D49B74"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.15:rc4:*:*:*:*:*:*","matchCriteriaId":"8C7B5B0E-4EEB-48F5-B4CF-0935A7633845"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.15:rc5:*:*:*:*:*:*","matchCriteriaId":"2D240580-3048-49B2-9E27-F115A9DF8224"}]}]},{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*","matchCriteriaId":"FA6FEEC2-9F11-4643-8827-749718254FED"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/02ad4ce144bd27f71f583f667fdf3b3ba0753477","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/12f703811af043d32b1c8a30001b2fa04d5cd0ac","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/399ec9ca8fc4999e676ff89a90184ec40031cf59","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/d41072906abec8bb8e01ed16afefbaa558908c89","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/d87392094f96e162fa5fa5a8640d70cc0952806f","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/fea4e317f9e7e1f449ce90dedc27a2d2a95bee5a","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"]},{"url":"https://lists.debian.org/debian-lts-announce/2025/08/msg00010.html","source":"af854a3a-2127-422b-91ae-364da2661108","tags":["Third Party Advisory"]}]}}]}