CVE-2025-40222

{
  "id": "CVE-2025-40222",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2025-12-04T16:16:14.627",
  "lastModified": "2026-10-19T19:10:00.130",
  "vulnStatus": "Deferred",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntty: serial: sh-sci: fix RSCI FIFO overrun handling\n\nThe receive error handling code is shared between RSCI and all other\nSCIF port types, but the RSCI overrun_reg is specified as a memory\noffset, while for other SCIF types it is an enum value used to index\ninto the sci_port_params->regs array, as mentioned above the\nsci_serial_in() function.\n\nFor RSCI, the overrun_reg is CSR (0x48), causing the sci_getreg() call\ninside the sci_handle_fifo_overrun() function to index outside the\nbounds of the regs array, which currently has a size of 20, as specified\nby SCI_NR_REGS.\n\nBecause of this, we end up accessing memory outside of RSCI's\nrsci_port_params structure, which, when interpreted as a plat_sci_reg,\nhappens to have a non-zero size, causing the following WARN when\nsci_serial_in() is called, as the accidental size does not match the\nsupported register sizes.\n\nThe existence of the overrun_reg needs to be checked because\nSCIx_SH3_SCIF_REGTYPE has overrun_reg set to SCLSR, but SCLSR is not\npresent in the regs array.\n\nAvoid calling sci_getreg() for port types which don't use standard\nregister handling.\n\nUse the ops->read_reg() and ops->write_reg() functions to properly read\nand write registers for RSCI, and change the type of the status variable\nto accommodate the 32-bit CSR register.\n\nsci_getreg() and sci_serial_in() are also called with overrun_reg in the\nsci_mpxed_interrupt() interrupt handler, but that code path is not used\nfor RSCI, as it does not have a muxed interrupt.\n\n------------[ cut here ]------------\nInvalid register access\nWARNING: CPU: 0 PID: 0 at drivers/tty/serial/sh-sci.c:522 sci_serial_in+0x38/0xac\nModules linked in: renesas_usbhs at24 rzt2h_adc industrialio_adc sha256 cfg80211 bluetooth ecdh_generic ecc rfkill fuse drm backlight ipv6\nCPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.17.0-rc1+ #30 PREEMPT\nHardware name: Renesas RZ/T2H EVK Board based on r9a09g077m44 (DT)\npstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)\npc : sci_serial_in+0x38/0xac\nlr : sci_serial_in+0x38/0xac\nsp : ffff800080003e80\nx29: ffff800080003e80 x28: ffff800082195b80 x27: 000000000000000d\nx26: ffff8000821956d0 x25: 0000000000000000 x24: ffff800082195b80\nx23: ffff000180e0d800 x22: 0000000000000010 x21: 0000000000000000\nx20: 0000000000000010 x19: ffff000180e72000 x18: 000000000000000a\nx17: ffff8002bcee7000 x16: ffff800080000000 x15: 0720072007200720\nx14: 0720072007200720 x13: 0720072007200720 x12: 0720072007200720\nx11: 0000000000000058 x10: 0000000000000018 x9 : ffff8000821a6a48\nx8 : 0000000000057fa8 x7 : 0000000000000406 x6 : ffff8000821fea48\nx5 : ffff00033ef88408 x4 : ffff8002bcee7000 x3 : ffff800082195b80\nx2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff800082195b80\nCall trace:\n sci_serial_in+0x38/0xac (P)\n sci_handle_fifo_overrun.isra.0+0x70/0x134\n sci_er_interrupt+0x50/0x39c\n __handle_irq_event_percpu+0x48/0x140\n handle_irq_event+0x44/0xb0\n handle_fasteoi_irq+0xf4/0x1a0\n handle_irq_desc+0x34/0x58\n generic_handle_domain_irq+0x1c/0x28\n gic_handle_irq+0x4c/0x140\n call_on_irq_stack+0x30/0x48\n do_interrupt_handler+0x80/0x84\n el1_interrupt+0x34/0x68\n el1h_64_irq_handler+0x18/0x24\n el1h_64_irq+0x6c/0x70\n default_idle_call+0x28/0x58 (P)\n do_idle+0x1f8/0x250\n cpu_startup_entry+0x34/0x3c\n rest_init+0xd8/0xe0\n console_on_rootfs+0x0/0x6c\n __primary_switched+0x88/0x90\n---[ end trace 0000000000000000 ]---"
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\ntty: serial: sh-sci: solucionar el manejo de desbordamiento de FIFO de RSCI\n\nEl código de manejo de errores de recepción es compartido entre RSCI y todos los demás tipos de puerto SCIF, pero el 'overrun_reg' de RSCI se especifica como un desplazamiento de memoria, mientras que para otros tipos de SCIF es un valor de enumeración utilizado para indexar en el array 'sci_port_params -> regs', como se mencionó arriba de la función 'sci_serial_in()'.\n\nPara RSCI, el 'overrun_reg' es CSR (0x48), lo que provoca que la llamada a 'sci_getreg()' dentro de la función 'sci_handle_fifo_overrun()' indexe fuera de los límites del array 'regs', el cual actualmente tiene un tamaño de 20, según lo especificado por 'SCI_NR_REGS'.\n\nDebido a esto, terminamos accediendo a memoria fuera de la estructura 'rsci_port_params' de RSCI, la cual, cuando se interpreta como un 'plat_sci_reg', resulta tener un tamaño distinto de cero, causando la siguiente ADVERTENCIA (WARN) cuando se llama a 'sci_serial_in()', ya que el tamaño accidental no coincide con los tamaños de registro admitidos.\n\nLa existencia del 'overrun_reg' necesita ser verificada porque 'SCIx_SH3_SCIF_REGTYPE' tiene el 'overrun_reg' configurado como SCLSR, pero SCLSR no está presente en el array 'regs'.\n\nEvitar llamar a 'sci_getreg()' para tipos de puerto que no utilizan el manejo de registros estándar.\n\nUsar las funciones 'ops -> read_reg()' y 'ops -> write_reg()' para leer y escribir registros correctamente para RSCI, y cambiar el tipo de la variable de estado para acomodar el registro CSR de 32 bits.\n\n'sci_getreg()' y 'sci_serial_in()' también son llamadas con 'overrun_reg' en el manejador de interrupciones 'sci_mpxed_interrupt()', pero esa ruta de código no se utiliza para RSCI, ya que no tiene una interrupción multiplexada.\n\n------------[ cut here ]------------\nAcceso a registro inválido\nWARNING: CPU: 0 PID: 0 at drivers/tty/serial/sh-sci.c:522 sci_serial_in+0x38/0xac\nModules linked in: renesas_usbhs at24 rzt2h_adc industrialio_adc sha256 cfg80211 bluetooth ecdh_generic ecc rfkill fuse drm backlight ipv6\nCPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.17.0-rc1+ #30 PREEMPT\nHardware name: Renesas RZ/T2H EVK Board based on r9a09g077m44 (DT)\npstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)\npc : sci_serial_in+0x38/0xac\nlr : sci_serial_in+0x38/0xac\nsp : ffff800080003e80\nx29: ffff800080003e80 x28: ffff800082195b80 x27: 000000000000000d\nx26: ffff8000821956d0 x25: 0000000000000000 x24: ffff800082195b80\nx23: ffff000180e0d800 x22: 0000000000000010 x21: 0000000000000000\nx20: 0000000000000010 x19: ffff000180e72000 x18: 000000000000000a\nx17: ffff8002bcee7000 x16: ffff800080000000 x15: 0720072007200720\nx14: 0720072007200720 x13: 0720072007200720 x12: 0720072007200720\nx11: 0000000000000058 x10: 0000000000000018 x9 : ffff8000821a6a48\nx8 : 0000000000057fa8 x7 : 0000000000000406 x6 : ffff8000821fea48\nx5 : ffff00033ef88408 x4 : ffff8002bcee7000 x3 : ffff800082195b80\nx2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff800082195b80\nRastro de llamadas:\n sci_serial_in+0x38/0xac (P)\n sci_handle_fifo_overrun.isra.0+0x70/0x134\n sci_er_interrupt+0x50/0x39c\n __handle_irq_event_percpu+0x48/0x140\n handle_irq_event+0x44/0xb0\n handle_fasteoi_irq+0xf4/0x1a0\n handle_irq_desc+0x34/0x58\n generic_handle_domain_irq+0x1c/0x28\n gic_handle_irq+0x4c/0x140\n call_on_irq_stack+0x30/0x48\n do_interrupt_handler+0x80/0x84\n el1_interrupt+0x34/0x68\n el1h_64_irq_handler+0x18/0x24\n el1h_64_irq+0x6c/0x70\n default_idle_call+0x28/0x58 (P)\n do_idle+0x1f8/0x250\n cpu_startup_entry+0x34/0x3c\n rest_init+0xd8/0xe0\n console_on_rootfs+0x0/0x6c\n __primary_switched+0x88/0x90\n---[ end trace 0000000000000000 ]---"
    }
  ],
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "programFiles": [
            "drivers/tty/serial/sh-sci.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "0666e3fe95ab55c295984f2f51277ec27d3f190c",
              "lessThan": "2ec9bbd09a6cdf5b8c726be34f29630faf585d07",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "0666e3fe95ab55c295984f2f51277ec27d3f190c",
              "lessThan": "ef8fef45c74b5a0059488fda2df65fa133f7d7d0",
              "versionType": "git",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "programFiles": [
            "drivers/tty/serial/sh-sci.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "6.17",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "6.17",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.17.6",
              "lessThanOrEqual": "6.17.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.18",
              "lessThanOrEqual": "*",
              "versionType": "original_commit_for_fix",
              "status": "unaffected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {},
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/2ec9bbd09a6cdf5b8c726be34f29630faf585d07",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/ef8fef45c74b5a0059488fda2df65fa133f7d7d0",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ]
}