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CVE-2023-53323

Estado: ModificadaMedia (5.5)—

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

ext2/dax: Fix ext2_setsize when len is page aligned

PAGE_ALIGN(x) macro gives the next highest value which is multiple of pagesize. But if x is already page aligned then it simply returns x. So, if x passed is 0 in dax_zero_range() function, that means the length gets passed as 0 to ->iomap_begin().

In ext2 it then calls ext2_get_blocks -> max_blocks as 0 and hits bug_on here in ext2_get_blocks(). BUG_ON(maxblocks == 0);

Instead we should be calling dax_truncate_page() here which takes care of it. i.e. it only calls dax_zero_range if the offset is not page/block aligned.

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This can be easily triggered with following on fsdax mounted pmem device.

dd if=/dev/zero of=file count=1 bs=512 truncate -s 0 file

Detalles técnicos trazas, registros y código del informe original
[79.525838] EXT2-fs (pmem0): DAX enabled. Warning: EXPERIMENTAL, use at your own risk
[79.529376] ext2 filesystem being mounted at /mnt1/test supports timestamps until 2038 (0x7fffffff)
[93.793207] ------------[ cut here ]------------
[93.795102] kernel BUG at fs/ext2/inode.c:637!
[93.796904] invalid opcode: 0000 [#1] PREEMPT SMP PTI
[93.798659] CPU: 0 PID: 1192 Comm: truncate Not tainted 6.3.0-rc2-xfstests-00056-g131086faa369 #139
[93.806459] RIP: 0010:ext2_get_blocks.constprop.0+0x524/0x610
<...>
[93.835298] Call Trace:
[93.836253]  <TASK>
[93.837103]  ? lock_acquire+0xf8/0x110
[93.838479]  ? d_lookup+0x69/0xd0
[93.839779]  ext2_iomap_begin+0xa7/0x1c0
[93.841154]  iomap_iter+0xc7/0x150
[93.842425]  dax_zero_range+0x6e/0xa0
[93.843813]  ext2_setsize+0x176/0x1b0
[93.845164]  ext2_setattr+0x151/0x200
[93.846467]  notify_change+0x341/0x4e0
[93.847805]  ? lock_acquire+0xf8/0x110
[93.849143]  ? do_truncate+0x74/0xe0
[93.850452]  ? do_truncate+0x84/0xe0
[93.851739]  do_truncate+0x84/0xe0
[93.852974]  do_sys_ftruncate+0x2b4/0x2f0
[93.854404]  do_syscall_64+0x3f/0x90
[93.855789]  entry_SYSCALL_64_after_hwframe+0x72/0xdc

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 (1)

Linux — Linux Kernel

CWE

Referencias

JSON original (NVD)

Mostrar
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  "id": "CVE-2023-53323",
  "cveTags": [],
  "metrics": {
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      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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          "role": "CISA Coordinator",
          "options": [
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              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
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          "version": "2.0.3",
          "timestamp": "2026-01-14T18:28:00.441739Z"
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          "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",
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  "published": "2025-09-16T17:15:38.410",
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  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\next2/dax: Fix ext2_setsize when len is page aligned\n\nPAGE_ALIGN(x) macro gives the next highest value which is multiple of\npagesize. But if x is already page aligned then it simply returns x.\nSo, if x passed is 0 in dax_zero_range() function, that means the\nlength gets passed as 0 to ->iomap_begin().\n\nIn ext2 it then calls ext2_get_blocks -> max_blocks as 0 and hits bug_on\nhere in ext2_get_blocks().\n\tBUG_ON(maxblocks == 0);\n\nInstead we should be calling dax_truncate_page() here which takes\ncare of it. i.e. it only calls dax_zero_range if the offset is not\npage/block aligned.\n\nThis can be easily triggered with following on fsdax mounted pmem\ndevice.\n\ndd if=/dev/zero of=file count=1 bs=512\ntruncate -s 0 file\n\n[79.525838] EXT2-fs (pmem0): DAX enabled. Warning: EXPERIMENTAL, use at your own risk\n[79.529376] ext2 filesystem being mounted at /mnt1/test supports timestamps until 2038 (0x7fffffff)\n[93.793207] ------------[ cut here ]------------\n[93.795102] kernel BUG at fs/ext2/inode.c:637!\n[93.796904] invalid opcode: 0000 [#1] PREEMPT SMP PTI\n[93.798659] CPU: 0 PID: 1192 Comm: truncate Not tainted 6.3.0-rc2-xfstests-00056-g131086faa369 #139\n[93.806459] RIP: 0010:ext2_get_blocks.constprop.0+0x524/0x610\n<...>\n[93.835298] Call Trace:\n[93.836253]  <TASK>\n[93.837103]  ? lock_acquire+0xf8/0x110\n[93.838479]  ? d_lookup+0x69/0xd0\n[93.839779]  ext2_iomap_begin+0xa7/0x1c0\n[93.841154]  iomap_iter+0xc7/0x150\n[93.842425]  dax_zero_range+0x6e/0xa0\n[93.843813]  ext2_setsize+0x176/0x1b0\n[93.845164]  ext2_setattr+0x151/0x200\n[93.846467]  notify_change+0x341/0x4e0\n[93.847805]  ? lock_acquire+0xf8/0x110\n[93.849143]  ? do_truncate+0x74/0xe0\n[93.850452]  ? do_truncate+0x84/0xe0\n[93.851739]  do_truncate+0x84/0xe0\n[93.852974]  do_sys_ftruncate+0x2b4/0x2f0\n[93.854404]  do_syscall_64+0x3f/0x90\n[93.855789]  entry_SYSCALL_64_after_hwframe+0x72/0xdc"
    }
  ],
  "lastModified": "2026-06-17T06:44:53.353",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "vulnerable": true,
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              "versionEndExcluding": "6.1.40",
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  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}