fkie_cve-2025-21881
Vulnerability from fkie_nvd
Published
2025-03-27 15:15
Modified
2025-11-03 20:17
Severity ?
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: uprobes: Reject the shared zeropage in uprobe_write_opcode() We triggered the following crash in syzkaller tests: BUG: Bad page state in process syz.7.38 pfn:1eff3 page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1eff3 flags: 0x3fffff00004004(referenced|reserved|node=0|zone=1|lastcpupid=0x1fffff) raw: 003fffff00004004 ffffe6c6c07bfcc8 ffffe6c6c07bfcc8 0000000000000000 raw: 0000000000000000 0000000000000000 00000000fffffffe 0000000000000000 page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x32/0x50 bad_page+0x69/0xf0 free_unref_page_prepare+0x401/0x500 free_unref_page+0x6d/0x1b0 uprobe_write_opcode+0x460/0x8e0 install_breakpoint.part.0+0x51/0x80 register_for_each_vma+0x1d9/0x2b0 __uprobe_register+0x245/0x300 bpf_uprobe_multi_link_attach+0x29b/0x4f0 link_create+0x1e2/0x280 __sys_bpf+0x75f/0xac0 __x64_sys_bpf+0x1a/0x30 do_syscall_64+0x56/0x100 entry_SYSCALL_64_after_hwframe+0x78/0xe2 BUG: Bad rss-counter state mm:00000000452453e0 type:MM_FILEPAGES val:-1 The following syzkaller test case can be used to reproduce: r2 = creat(&(0x7f0000000000)='./file0\x00', 0x8) write$nbd(r2, &(0x7f0000000580)=ANY=[], 0x10) r4 = openat(0xffffffffffffff9c, &(0x7f0000000040)='./file0\x00', 0x42, 0x0) mmap$IORING_OFF_SQ_RING(&(0x7f0000ffd000/0x3000)=nil, 0x3000, 0x0, 0x12, r4, 0x0) r5 = userfaultfd(0x80801) ioctl$UFFDIO_API(r5, 0xc018aa3f, &(0x7f0000000040)={0xaa, 0x20}) r6 = userfaultfd(0x80801) ioctl$UFFDIO_API(r6, 0xc018aa3f, &(0x7f0000000140)) ioctl$UFFDIO_REGISTER(r6, 0xc020aa00, &(0x7f0000000100)={{&(0x7f0000ffc000/0x4000)=nil, 0x4000}, 0x2}) ioctl$UFFDIO_ZEROPAGE(r5, 0xc020aa04, &(0x7f0000000000)={{&(0x7f0000ffd000/0x1000)=nil, 0x1000}}) r7 = bpf$PROG_LOAD(0x5, &(0x7f0000000140)={0x2, 0x3, &(0x7f0000000200)=ANY=[@ANYBLOB="1800000000120000000000000000000095"], &(0x7f0000000000)='GPL\x00', 0x7, 0x0, 0x0, 0x0, 0x0, '\x00', 0x0, @fallback=0x30, 0xffffffffffffffff, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x10, 0x0, @void, @value}, 0x94) bpf$BPF_LINK_CREATE_XDP(0x1c, &(0x7f0000000040)={r7, 0x0, 0x30, 0x1e, @val=@uprobe_multi={&(0x7f0000000080)='./file0\x00', &(0x7f0000000100)=[0x2], 0x0, 0x0, 0x1}}, 0x40) The cause is that zero pfn is set to the PTE without increasing the RSS count in mfill_atomic_pte_zeropage() and the refcount of zero folio does not increase accordingly. Then, the operation on the same pfn is performed in uprobe_write_opcode()->__replace_page() to unconditional decrease the RSS count and old_folio's refcount. Therefore, two bugs are introduced: 1. The RSS count is incorrect, when process exit, the check_mm() report error "Bad rss-count". 2. The reserved folio (zero folio) is freed when folio->refcount is zero, then free_pages_prepare->free_page_is_bad() report error "Bad page state". There is more, the following warning could also theoretically be triggered: __replace_page() -> ... -> folio_remove_rmap_pte() -> VM_WARN_ON_FOLIO(is_zero_folio(folio), folio) Considering that uprobe hit on the zero folio is a very rare case, just reject zero old folio immediately after get_user_page_vma_remote(). [ mingo: Cleaned up the changelog ]
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0b6f19714588cf2366b0364234f97ba963688f63Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/13cca2b73e2b0ec3ea6d6615d615395621d22752Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/54011fc94422f094eaf47555284de70a4bc32bb9Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/bddf10d26e6e5114e7415a0e442ec6f51a559468Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/c4cb2bfa99513311886c1eb5c1c2ac26f3338a6ePatch
af854a3a-2127-422b-91ae-364da2661108https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel 6.14
linux linux_kernel 6.14
linux linux_kernel 6.14
linux linux_kernel 6.14


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  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nuprobes: Reject the shared zeropage in uprobe_write_opcode()\n\nWe triggered the following crash in syzkaller tests:\n\n  BUG: Bad page state in process syz.7.38  pfn:1eff3\n  page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1eff3\n  flags: 0x3fffff00004004(referenced|reserved|node=0|zone=1|lastcpupid=0x1fffff)\n  raw: 003fffff00004004 ffffe6c6c07bfcc8 ffffe6c6c07bfcc8 0000000000000000\n  raw: 0000000000000000 0000000000000000 00000000fffffffe 0000000000000000\n  page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set\n  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014\n  Call Trace:\n   \u003cTASK\u003e\n   dump_stack_lvl+0x32/0x50\n   bad_page+0x69/0xf0\n   free_unref_page_prepare+0x401/0x500\n   free_unref_page+0x6d/0x1b0\n   uprobe_write_opcode+0x460/0x8e0\n   install_breakpoint.part.0+0x51/0x80\n   register_for_each_vma+0x1d9/0x2b0\n   __uprobe_register+0x245/0x300\n   bpf_uprobe_multi_link_attach+0x29b/0x4f0\n   link_create+0x1e2/0x280\n   __sys_bpf+0x75f/0xac0\n   __x64_sys_bpf+0x1a/0x30\n   do_syscall_64+0x56/0x100\n   entry_SYSCALL_64_after_hwframe+0x78/0xe2\n\n   BUG: Bad rss-counter state mm:00000000452453e0 type:MM_FILEPAGES val:-1\n\nThe following syzkaller test case can be used to reproduce:\n\n  r2 = creat(\u0026(0x7f0000000000)=\u0027./file0\\x00\u0027, 0x8)\n  write$nbd(r2, \u0026(0x7f0000000580)=ANY=[], 0x10)\n  r4 = openat(0xffffffffffffff9c, \u0026(0x7f0000000040)=\u0027./file0\\x00\u0027, 0x42, 0x0)\n  mmap$IORING_OFF_SQ_RING(\u0026(0x7f0000ffd000/0x3000)=nil, 0x3000, 0x0, 0x12, r4, 0x0)\n  r5 = userfaultfd(0x80801)\n  ioctl$UFFDIO_API(r5, 0xc018aa3f, \u0026(0x7f0000000040)={0xaa, 0x20})\n  r6 = userfaultfd(0x80801)\n  ioctl$UFFDIO_API(r6, 0xc018aa3f, \u0026(0x7f0000000140))\n  ioctl$UFFDIO_REGISTER(r6, 0xc020aa00, \u0026(0x7f0000000100)={{\u0026(0x7f0000ffc000/0x4000)=nil, 0x4000}, 0x2})\n  ioctl$UFFDIO_ZEROPAGE(r5, 0xc020aa04, \u0026(0x7f0000000000)={{\u0026(0x7f0000ffd000/0x1000)=nil, 0x1000}})\n  r7 = bpf$PROG_LOAD(0x5, \u0026(0x7f0000000140)={0x2, 0x3, \u0026(0x7f0000000200)=ANY=[@ANYBLOB=\"1800000000120000000000000000000095\"], \u0026(0x7f0000000000)=\u0027GPL\\x00\u0027, 0x7, 0x0, 0x0, 0x0, 0x0, \u0027\\x00\u0027, 0x0, @fallback=0x30, 0xffffffffffffffff, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x10, 0x0, @void, @value}, 0x94)\n  bpf$BPF_LINK_CREATE_XDP(0x1c, \u0026(0x7f0000000040)={r7, 0x0, 0x30, 0x1e, @val=@uprobe_multi={\u0026(0x7f0000000080)=\u0027./file0\\x00\u0027, \u0026(0x7f0000000100)=[0x2], 0x0, 0x0, 0x1}}, 0x40)\n\nThe cause is that zero pfn is set to the PTE without increasing the RSS\ncount in mfill_atomic_pte_zeropage() and the refcount of zero folio does\nnot increase accordingly. Then, the operation on the same pfn is performed\nin uprobe_write_opcode()-\u003e__replace_page() to unconditional decrease the\nRSS count and old_folio\u0027s refcount.\n\nTherefore, two bugs are introduced:\n\n 1. The RSS count is incorrect, when process exit, the check_mm() report\n    error \"Bad rss-count\".\n\n 2. The reserved folio (zero folio) is freed when folio-\u003erefcount is zero,\n    then free_pages_prepare-\u003efree_page_is_bad() report error\n    \"Bad page state\".\n\nThere is more, the following warning could also theoretically be triggered:\n\n  __replace_page()\n    -\u003e ...\n      -\u003e folio_remove_rmap_pte()\n        -\u003e VM_WARN_ON_FOLIO(is_zero_folio(folio), folio)\n\nConsidering that uprobe hit on the zero folio is a very rare case, just\nreject zero old folio immediately after get_user_page_vma_remote().\n\n[ mingo: Cleaned up the changelog ]"
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: uprobes: Rechazar la p\u00e1gina cero compartida en uprobe_write_opcode() Activamos el siguiente fallo en las pruebas de syzkaller: ERROR: Estado de p\u00e1gina incorrecto en el proceso syz.7.38 pfn:1eff3 page: refcount:0 mapcount:0 mapping:000000000000000 index:0x0 pfn:0x1eff3 flags: 0x3fffff00004004(referenced|reserved|node=0|zone=1|lastcpupid=0x1fffff) raw: 003fffff00004004 ffffe6c6c07bfcc8 ffffe6c6c07bfcc8 000000000000000 raw: 000000000000000 0000000000000000 00000000ffffffffe 0000000000000000 p\u00e1gina volcada porque: PAGE_FLAGS_CHECK_AT_FREE indicador(es) establecido(s) Nombre del hardware: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 01/04/2014 Seguimiento de llamadas:  dump_stack_lvl+0x32/0x50 bad_page+0x69/0xf0 free_unref_page_prepare+0x401/0x500 free_unref_page+0x6d/0x1b0 uprobe_write_opcode+0x460/0x8e0 install_breakpoint.part.0+0x51/0x80 register_for_each_vma+0x1d9/0x2b0 __uprobe_register+0x245/0x300 bpf_uprobe_multi_link_attach+0x29b/0x4f0 link_create+0x1e2/0x280 __sys_bpf+0x75f/0xac0 __x64_sys_bpf+0x1a/0x30 do_syscall_64+0x56/0x100 entry_SYSCALL_64_after_hwframe+0x78/0xe2 BUG: Bad rss-counter state mm:00000000452453e0 type:MM_FILEPAGES val:-1 The following syzkaller test case can be used to reproduce: r2 = creat(\u0026amp;(0x7f0000000000)=\u0027./file0\\x00\u0027, 0x8) write$nbd(r2, \u0026amp;(0x7f0000000580)=ANY=[], 0x10) r4 = openat(0xffffffffffffff9c, \u0026amp;(0x7f0000000040)=\u0027./file0\\x00\u0027, 0x42, 0x0) mmap$IORING_OFF_SQ_RING(\u0026amp;(0x7f0000ffd000/0x3000)=nil, 0x3000, 0x0, 0x12, r4, 0x0) r5 = userfaultfd(0x80801) ioctl$UFFDIO_API(r5, 0xc018aa3f, \u0026amp;(0x7f0000000040)={0xaa, 0x20}) r6 = userfaultfd(0x80801) ioctl$UFFDIO_API(r6, 0xc018aa3f, \u0026amp;(0x7f0000000140)) ioctl$UFFDIO_REGISTER(r6, 0xc020aa00, \u0026amp;(0x7f0000000100)={{\u0026amp;(0x7f0000ffc000/0x4000)=nil, 0x4000}, 0x2}) ioctl$UFFDIO_ZEROPAGE(r5, 0xc020aa04, \u0026amp;(0x7f0000000000)={{\u0026amp;(0x7f0000ffd000/0x1000)=nil, 0x1000}}) r7 = bpf$PROG_LOAD(0x5, \u0026amp;(0x7f0000000140)={0x2, 0x3, \u0026amp;(0x7f0000000200)=ANY=[@ANYBLOB=\"1800000000120000000000000000000095\"], \u0026amp;(0x7f0000000000)=\u0027GPL\\x00\u0027, 0x7, 0x0, 0x0, 0x0, 0x0, \u0027\\x00\u0027, 0x0, @fallback=0x30, 0xffffffffffffffff, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x10, 0x0, @void, @value}, 0x94) bpf$BPF_LINK_CREATE_XDP(0x1c, \u0026amp;(0x7f0000000040)={r7, 0x0, 0x30, 0x1e, @val=@uprobe_multi={\u0026amp;(0x7f0000000080)=\u0027./file0\\x00\u0027, \u0026amp;(0x7f0000000100)=[0x2], 0x0, 0x0, 0x1}}, 0x40) La causa es que cero El pfn se establece en el PTE sin aumentar el recuento RSS en mfill_atomic_pte_zeropage() y el recuento de referencias del folio cero no aumenta en consecuencia. Luego, se realiza la misma operaci\u00f3n en el pfn en uprobe_write_opcode()-\u0026gt;__replace_page() para disminuir incondicionalmente el recuento RSS y el recuento de referencias de old_folio. Por lo tanto, se introducen dos errores: 1. El recuento RSS es incorrecto; al finalizar el proceso, check_mm() informa el error \"Bad RSS-count\" (recuento RSS incorrecto). 2. El folio reservado (folio cero) se libera cuando folio-\u0026gt;refcount es cero; entonces, free_pages_prepare-\u0026gt;free_page_is_bad() informa el error \"Bad page state\" (estado de p\u00e1gina incorrecto). Hay m\u00e1s, la siguiente advertencia tambi\u00e9n podr\u00eda activarse te\u00f3ricamente: __replace_page() -\u0026gt; ... -\u0026gt; folio_remove_rmap_pte() -\u0026gt; VM_WARN_ON_FOLIO(is_zero_folio(folio), folio) Teniendo en cuenta que el impacto de uprobe en el folio cero es un caso muy raro, simplemente rechace el folio antiguo cero inmediatamente despu\u00e9s de get_user_page_vma_remote(). [ mingo: Se limpi\u00f3 el registro de cambios ]"
    }
  ],
  "id": "CVE-2025-21881",
  "lastModified": "2025-11-03T20:17:25.100",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 5.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2025-03-27T15:15:56.000",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/0b6f19714588cf2366b0364234f97ba963688f63"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/13cca2b73e2b0ec3ea6d6615d615395621d22752"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/54011fc94422f094eaf47555284de70a4bc32bb9"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/bddf10d26e6e5114e7415a0e442ec6f51a559468"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/c4cb2bfa99513311886c1eb5c1c2ac26f3338a6e"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-noinfo"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}


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