CVE-2025-21881 (GCVE-0-2025-21881)
Vulnerability from cvelistv5
Published
2025-03-27 14:57
Modified
2025-05-04 07:23
Severity ?
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
Impacted products
Vendor Product Version
Linux Linux Version: 2b144498350860b6ee9dc57ff27a93ad488de5dc
Version: 2b144498350860b6ee9dc57ff27a93ad488de5dc
Version: 2b144498350860b6ee9dc57ff27a93ad488de5dc
Version: 2b144498350860b6ee9dc57ff27a93ad488de5dc
Version: 2b144498350860b6ee9dc57ff27a93ad488de5dc
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/events/uprobes.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "c4cb2bfa99513311886c1eb5c1c2ac26f3338a6e",
              "status": "affected",
              "version": "2b144498350860b6ee9dc57ff27a93ad488de5dc",
              "versionType": "git"
            },
            {
              "lessThan": "0b6f19714588cf2366b0364234f97ba963688f63",
              "status": "affected",
              "version": "2b144498350860b6ee9dc57ff27a93ad488de5dc",
              "versionType": "git"
            },
            {
              "lessThan": "13cca2b73e2b0ec3ea6d6615d615395621d22752",
              "status": "affected",
              "version": "2b144498350860b6ee9dc57ff27a93ad488de5dc",
              "versionType": "git"
            },
            {
              "lessThan": "54011fc94422f094eaf47555284de70a4bc32bb9",
              "status": "affected",
              "version": "2b144498350860b6ee9dc57ff27a93ad488de5dc",
              "versionType": "git"
            },
            {
              "lessThan": "bddf10d26e6e5114e7415a0e442ec6f51a559468",
              "status": "affected",
              "version": "2b144498350860b6ee9dc57ff27a93ad488de5dc",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "kernel/events/uprobes.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "3.5"
            },
            {
              "lessThan": "3.5",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.130",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.81",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.18",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.13.*",
              "status": "unaffected",
              "version": "6.13.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.14",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.130",
                  "versionStartIncluding": "3.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.81",
                  "versionStartIncluding": "3.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.18",
                  "versionStartIncluding": "3.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.13.6",
                  "versionStartIncluding": "3.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.14",
                  "versionStartIncluding": "3.5",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "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 ]"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-05-04T07:23:14.242Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/c4cb2bfa99513311886c1eb5c1c2ac26f3338a6e"
        },
        {
          "url": "https://git.kernel.org/stable/c/0b6f19714588cf2366b0364234f97ba963688f63"
        },
        {
          "url": "https://git.kernel.org/stable/c/13cca2b73e2b0ec3ea6d6615d615395621d22752"
        },
        {
          "url": "https://git.kernel.org/stable/c/54011fc94422f094eaf47555284de70a4bc32bb9"
        },
        {
          "url": "https://git.kernel.org/stable/c/bddf10d26e6e5114e7415a0e442ec6f51a559468"
        }
      ],
      "title": "uprobes: Reject the shared zeropage in uprobe_write_opcode()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-21881",
    "datePublished": "2025-03-27T14:57:10.241Z",
    "dateReserved": "2024-12-29T08:45:45.782Z",
    "dateUpdated": "2025-05-04T07:23:14.242Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-21881\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-03-27T15:15:56.000\",\"lastModified\":\"2025-03-27T16:45:12.210\",\"vulnStatus\":\"Awaiting Analysis\",\"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 ]\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/0b6f19714588cf2366b0364234f97ba963688f63\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/13cca2b73e2b0ec3ea6d6615d615395621d22752\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/54011fc94422f094eaf47555284de70a4bc32bb9\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/bddf10d26e6e5114e7415a0e442ec6f51a559468\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/c4cb2bfa99513311886c1eb5c1c2ac26f3338a6e\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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