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CVE-2025-39885

Estado: AnalizadaMedia (5.5)—

In the Linux kernel, the following vulnerability has been resolved:

ocfs2: fix recursive semaphore deadlock in fiemap call

syzbot detected a OCFS2 hang due to a recursive semaphore on a FS_IOC_FIEMAP of the extent list on a specially crafted mmap file.

ocfs2_fiemap() takes a read lock of the ip_alloc_sem semaphore (since v2.6.22-527-g7307de80510a) and calls fiemap_fill_next_extent() to read the extent list of this running mmap executable. The user supplied buffer to hold the fiemap information page faults calling ocfs2_page_mkwrite() which will take a write lock (since v2.6.27-38-g00dc417fa3e7) of the same semaphore. This recursive semaphore will hold filesystem locks and causes a hang of the fileystem.

Leer descripción completaMostrar menos

The ip_alloc_sem protects the inode extent list and size. Release the read semphore before calling fiemap_fill_next_extent() in ocfs2_fiemap() and ocfs2_fiemap_inline(). This does an unnecessary semaphore lock/unlock on the last extent but simplifies the error path.

Detalles técnicos trazas, registros y código del informe original
context_switch kernel/sched/core.c:5357 [inline]
   __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
   __schedule_loop kernel/sched/core.c:7043 [inline]
   schedule+0x165/0x360 kernel/sched/core.c:7058
   schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7115
   rwsem_down_write_slowpath+0x872/0xfe0 kernel/locking/rwsem.c:1185
   __down_write_common kernel/locking/rwsem.c:1317 [inline]
   __down_write kernel/locking/rwsem.c:1326 [inline]
   down_write+0x1ab/0x1f0 kernel/locking/rwsem.c:1591
   ocfs2_page_mkwrite+0x2ff/0xc40 fs/ocfs2/mmap.c:142
   do_page_mkwrite+0x14d/0x310 mm/memory.c:3361
   wp_page_shared mm/memory.c:3762 [inline]
   do_wp_page+0x268d/0x5800 mm/memory.c:3981
   handle_pte_fault mm/memory.c:6068 [inline]
   __handle_mm_fault+0x1033/0x5440 mm/memory.c:6195
   handle_mm_fault+0x40a/0x8e0 mm/memory.c:6364
   do_user_addr_fault+0x764/0x1390 arch/x86/mm/fault.c:1387
   handle_page_fault arch/x86/mm/fault.c:1476 [inline]
   exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532
   asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
RIP: 0010:copy_user_generic arch/x86/include/asm/uaccess_64.h:126 [inline]
RIP: 0010:raw_copy_to_user arch/x86/include/asm/uaccess_64.h:147 [inline]
RIP: 0010:_inline_copy_to_user include/linux/uaccess.h:197 [inline]
RIP: 0010:_copy_to_user+0x85/0xb0 lib/usercopy.c:26
Code: e8 00 bc f7 fc 4d 39 fc 72 3d 4d 39 ec 77 38 e8 91 b9 f7 fc 4c 89
f7 89 de e8 47 25 5b fd 0f 01 cb 4c 89 ff 48 89 d9 4c 89 f6 <f3> a4 0f
1f 00 48 89 cb 0f 01 ca 48 89 d8 5b 41 5c 41 5d 41 5e 41
RSP: 0018:ffffc9000403f950 EFLAGS: 00050256
RAX: ffffffff84c7f101 RBX: 0000000000000038 RCX: 0000000000000038
RDX: 0000000000000000 RSI: ffffc9000403f9e0 RDI: 0000200000000060
RBP: ffffc9000403fa90 R08: ffffc9000403fa17 R09: 1ffff92000807f42
R10: dffffc0000000000 R11: fffff52000807f43 R12: 0000200000000098
R13: 00007ffffffff000 R14: ffffc9000403f9e0 R15: 0000200000000060
   copy_to_user include/linux/uaccess.h:225 [inline]
   fiemap_fill_next_extent+0x1c0/0x390 fs/ioctl.c:145
   ocfs2_fiemap+0x888/0xc90 fs/ocfs2/extent_map.c:806
   ioctl_fiemap fs/ioctl.c:220 [inline]
   do_vfs_ioctl+0x1173/0x1430 fs/ioctl.c:532
   __do_sys_ioctl fs/ioctl.c:596 [inline]
   __se_sys_ioctl+0x82/0x170 fs/ioctl.c:584
   do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
   do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
   entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5f13850fd9
RSP: 002b:00007ffe3b3518b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000200000000000 RCX: 00007f5f13850fd9
RDX: 0000200000000040 RSI: 00000000c020660b RDI: 0000000000000004
RBP: 6165627472616568 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe3b3518f0
R13: 00007ffe3b351b18 R14: 431bde82d7b634db R15: 00007f5f1389a03b

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

Tecnologías afectadas (2)

CWE

Referencias

JSON original (NVD)

Mostrar
{
  "id": "CVE-2025-39885",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
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        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 5.5,
          "attackVector": "LOCAL",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 1.8
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            },
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              "version": "6.1.153",
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            },
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              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
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          "programFiles": [
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          "defaultStatus": "affected"
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  "published": "2025-09-23T06:15:48.370",
  "references": [
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      "tags": [
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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      "tags": [
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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      "tags": [
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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      "tags": [
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
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      "tags": [
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      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
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  "vulnStatus": "Analyzed",
  "weaknesses": [
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      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-667"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nocfs2: fix recursive semaphore deadlock in fiemap call\n\nsyzbot detected a OCFS2 hang due to a recursive semaphore on a\nFS_IOC_FIEMAP of the extent list on a specially crafted mmap file.\n\ncontext_switch kernel/sched/core.c:5357 [inline]\n   __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961\n   __schedule_loop kernel/sched/core.c:7043 [inline]\n   schedule+0x165/0x360 kernel/sched/core.c:7058\n   schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7115\n   rwsem_down_write_slowpath+0x872/0xfe0 kernel/locking/rwsem.c:1185\n   __down_write_common kernel/locking/rwsem.c:1317 [inline]\n   __down_write kernel/locking/rwsem.c:1326 [inline]\n   down_write+0x1ab/0x1f0 kernel/locking/rwsem.c:1591\n   ocfs2_page_mkwrite+0x2ff/0xc40 fs/ocfs2/mmap.c:142\n   do_page_mkwrite+0x14d/0x310 mm/memory.c:3361\n   wp_page_shared mm/memory.c:3762 [inline]\n   do_wp_page+0x268d/0x5800 mm/memory.c:3981\n   handle_pte_fault mm/memory.c:6068 [inline]\n   __handle_mm_fault+0x1033/0x5440 mm/memory.c:6195\n   handle_mm_fault+0x40a/0x8e0 mm/memory.c:6364\n   do_user_addr_fault+0x764/0x1390 arch/x86/mm/fault.c:1387\n   handle_page_fault arch/x86/mm/fault.c:1476 [inline]\n   exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532\n   asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623\nRIP: 0010:copy_user_generic arch/x86/include/asm/uaccess_64.h:126 [inline]\nRIP: 0010:raw_copy_to_user arch/x86/include/asm/uaccess_64.h:147 [inline]\nRIP: 0010:_inline_copy_to_user include/linux/uaccess.h:197 [inline]\nRIP: 0010:_copy_to_user+0x85/0xb0 lib/usercopy.c:26\nCode: e8 00 bc f7 fc 4d 39 fc 72 3d 4d 39 ec 77 38 e8 91 b9 f7 fc 4c 89\nf7 89 de e8 47 25 5b fd 0f 01 cb 4c 89 ff 48 89 d9 4c 89 f6 <f3> a4 0f\n1f 00 48 89 cb 0f 01 ca 48 89 d8 5b 41 5c 41 5d 41 5e 41\nRSP: 0018:ffffc9000403f950 EFLAGS: 00050256\nRAX: ffffffff84c7f101 RBX: 0000000000000038 RCX: 0000000000000038\nRDX: 0000000000000000 RSI: ffffc9000403f9e0 RDI: 0000200000000060\nRBP: ffffc9000403fa90 R08: ffffc9000403fa17 R09: 1ffff92000807f42\nR10: dffffc0000000000 R11: fffff52000807f43 R12: 0000200000000098\nR13: 00007ffffffff000 R14: ffffc9000403f9e0 R15: 0000200000000060\n   copy_to_user include/linux/uaccess.h:225 [inline]\n   fiemap_fill_next_extent+0x1c0/0x390 fs/ioctl.c:145\n   ocfs2_fiemap+0x888/0xc90 fs/ocfs2/extent_map.c:806\n   ioctl_fiemap fs/ioctl.c:220 [inline]\n   do_vfs_ioctl+0x1173/0x1430 fs/ioctl.c:532\n   __do_sys_ioctl fs/ioctl.c:596 [inline]\n   __se_sys_ioctl+0x82/0x170 fs/ioctl.c:584\n   do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]\n   do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94\n   entry_SYSCALL_64_after_hwframe+0x77/0x7f\nRIP: 0033:0x7f5f13850fd9\nRSP: 002b:00007ffe3b3518b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010\nRAX: ffffffffffffffda RBX: 0000200000000000 RCX: 00007f5f13850fd9\nRDX: 0000200000000040 RSI: 00000000c020660b RDI: 0000000000000004\nRBP: 6165627472616568 R08: 0000000000000000 R09: 0000000000000000\nR10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe3b3518f0\nR13: 00007ffe3b351b18 R14: 431bde82d7b634db R15: 00007f5f1389a03b\n\nocfs2_fiemap() takes a read lock of the ip_alloc_sem semaphore (since\nv2.6.22-527-g7307de80510a) and calls fiemap_fill_next_extent() to read the\nextent list of this running mmap executable.  The user supplied buffer to\nhold the fiemap information page faults calling ocfs2_page_mkwrite() which\nwill take a write lock (since v2.6.27-38-g00dc417fa3e7) of the same\nsemaphore.  This recursive semaphore will hold filesystem locks and causes\na hang of the fileystem.\n\nThe ip_alloc_sem protects the inode extent list and size.  Release the\nread semphore before calling fiemap_fill_next_extent() in ocfs2_fiemap()\nand ocfs2_fiemap_inline().  This does an unnecessary semaphore lock/unlock\non the last extent but simplifies the error path."
    }
  ],
  "lastModified": "2026-06-17T09:18:44.800",
  "configurations": [
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}