fkie_cve-2021-47636
Vulnerability from fkie_nvd
Published
2025-02-26 06:37
Modified
2025-10-01 20:15
Severity ?
7.1 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
7.1 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: ubifs: Fix read out-of-bounds in ubifs_wbuf_write_nolock() Function ubifs_wbuf_write_nolock() may access buf out of bounds in following process: ubifs_wbuf_write_nolock(): aligned_len = ALIGN(len, 8); // Assume len = 4089, aligned_len = 4096 if (aligned_len <= wbuf->avail) ... // Not satisfy if (wbuf->used) { ubifs_leb_write() // Fill some data in avail wbuf len -= wbuf->avail; // len is still not 8-bytes aligned aligned_len -= wbuf->avail; } n = aligned_len >> c->max_write_shift; if (n) { n <<= c->max_write_shift; err = ubifs_leb_write(c, wbuf->lnum, buf + written, wbuf->offs, n); // n > len, read out of bounds less than 8(n-len) bytes } , which can be catched by KASAN: ========================================================= BUG: KASAN: slab-out-of-bounds in ecc_sw_hamming_calculate+0x1dc/0x7d0 Read of size 4 at addr ffff888105594ff8 by task kworker/u8:4/128 Workqueue: writeback wb_workfn (flush-ubifs_0_0) Call Trace: kasan_report.cold+0x81/0x165 nand_write_page_swecc+0xa9/0x160 ubifs_leb_write+0xf2/0x1b0 [ubifs] ubifs_wbuf_write_nolock+0x421/0x12c0 [ubifs] write_head+0xdc/0x1c0 [ubifs] ubifs_jnl_write_inode+0x627/0x960 [ubifs] wb_workfn+0x8af/0xb80 Function ubifs_wbuf_write_nolock() accepts that parameter 'len' is not 8 bytes aligned, the 'len' represents the true length of buf (which is allocated in 'ubifs_jnl_xxx', eg. ubifs_jnl_write_inode), so ubifs_wbuf_write_nolock() must handle the length read from 'buf' carefully to write leb safely. Fetch a reproducer in [Link].
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/07a209fadee7b53b46858538e1177597273862e4Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/3b7fb89135a20587d57f8877c02e25003e9edbdfPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/4f2262a334641e05f645364d5ade1f565c85f20bPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/5343575aa11c5d7044107d59d43f84aec01312b0Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a7054aaf1909cf40489c0ec1b728fdcf79c751a6Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/b80ccbec0e4804436c382d7dd60e943c386ed83aPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e09fa5318d51f522e1af4fbaf8f74999355980c8Patch
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *


To clipboard 

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  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nubifs: Fix read out-of-bounds in ubifs_wbuf_write_nolock()\n\nFunction ubifs_wbuf_write_nolock() may access buf out of bounds in\nfollowing process:\n\nubifs_wbuf_write_nolock():\n  aligned_len = ALIGN(len, 8);   // Assume len = 4089, aligned_len = 4096\n  if (aligned_len \u003c= wbuf-\u003eavail) ... // Not satisfy\n  if (wbuf-\u003eused) {\n    ubifs_leb_write()  // Fill some data in avail wbuf\n    len -= wbuf-\u003eavail;   // len is still not 8-bytes aligned\n    aligned_len -= wbuf-\u003eavail;\n  }\n  n = aligned_len \u003e\u003e c-\u003emax_write_shift;\n  if (n) {\n    n \u003c\u003c= c-\u003emax_write_shift;\n    err = ubifs_leb_write(c, wbuf-\u003elnum, buf + written,\n                          wbuf-\u003eoffs, n);\n    // n \u003e len, read out of bounds less than 8(n-len) bytes\n  }\n\n, which can be catched by KASAN:\n  =========================================================\n  BUG: KASAN: slab-out-of-bounds in ecc_sw_hamming_calculate+0x1dc/0x7d0\n  Read of size 4 at addr ffff888105594ff8 by task kworker/u8:4/128\n  Workqueue: writeback wb_workfn (flush-ubifs_0_0)\n  Call Trace:\n    kasan_report.cold+0x81/0x165\n    nand_write_page_swecc+0xa9/0x160\n    ubifs_leb_write+0xf2/0x1b0 [ubifs]\n    ubifs_wbuf_write_nolock+0x421/0x12c0 [ubifs]\n    write_head+0xdc/0x1c0 [ubifs]\n    ubifs_jnl_write_inode+0x627/0x960 [ubifs]\n    wb_workfn+0x8af/0xb80\n\nFunction ubifs_wbuf_write_nolock() accepts that parameter \u0027len\u0027 is not 8\nbytes aligned, the \u0027len\u0027 represents the true length of buf (which is\nallocated in \u0027ubifs_jnl_xxx\u0027, eg. ubifs_jnl_write_inode), so\nubifs_wbuf_write_nolock() must handle the length read from \u0027buf\u0027 carefully\nto write leb safely.\n\nFetch a reproducer in [Link]."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: ubifs: Se corrige la lectura fuera de los l\u00edmites en la funci\u00f3n ubifs_wbuf_write_nolock() ubifs_wbuf_write_nolock() puede acceder a buf fuera de los l\u00edmites en el siguiente proceso: ubifs_wbuf_write_nolock(): classified_len = ALIGN(len, 8); // Supongamos que len = 4089, classified_len = 4096 if (aligned_len \u0026lt;= wbuf-\u0026gt;avail) ... // No satisface if (wbuf-\u0026gt;used) { ubifs_leb_write() // Complete algunos datos en avail wbuf len -= wbuf-\u0026gt;avail; // len a\u00fan no est\u00e1 alineado a 8 bytes classified_len -= wbuf-\u0026gt;avail; } n = classified_len \u0026gt;\u0026gt; c-\u0026gt;max_write_shift; if (n) { n \u0026lt;\u0026lt;= c-\u0026gt;max_write_shift; err = ubifs_leb_write(c, wbuf-\u0026gt;lnum, buf + escrito, wbuf-\u0026gt;offs, n); // n \u0026gt; len, lectura fuera de los l\u00edmites menor a 8(n-len) bytes }, lo cual puede ser detectado por KASAN: =========================================================== ERROR: KASAN: slab fuera de los l\u00edmites en ecc_sw_hamming_calculate+0x1dc/0x7d0 Lectura de tama\u00f1o 4 en la direcci\u00f3n ffff888105594ff8 por la tarea kworker/u8:4/128 Cola de trabajo: escritura diferida wb_workfn (flush-ubifs_0_0) Rastreo de llamadas: kasan_report.cold+0x81/0x165 nand_write_page_swecc+0xa9/0x160 ubifs_leb_write+0xf2/0x1b0 [ubifs] ubifs_wbuf_write_nolock+0x421/0x12c0 [ubifs] write_head+0xdc/0x1c0 [ubifs] ubifs_jnl_write_inode+0x627/0x960 [ubifs] wb_workfn+0x8af/0xb80 La funci\u00f3n ubifs_wbuf_write_nolock() acepta que el par\u00e1metro \u0027len\u0027 no est\u00e9 alineado con 8 bytes, \u0027len\u0027 representa la longitud verdadera de buf (que est\u00e1 asignada en \u0027ubifs_jnl_xxx\u0027, p. ej. ubifs_jnl_write_inode), por lo que ubifs_wbuf_write_nolock() debe manejar la longitud le\u00edda de \u0027buf\u0027 con cuidado para escribir leb de forma segura. Obtenga un reproductor en [Enlace]."
    }
  ],
  "id": "CVE-2021-47636",
  "lastModified": "2025-10-01T20:15:40.343",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.1,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.2,
        "source": "nvd@nist.gov",
        "type": "Primary"
      },
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.1,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
          "version": "3.1"
        },
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        "impactScore": 5.2,
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
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  "published": "2025-02-26T06:37:05.377",
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  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
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          "lang": "en",
          "value": "CWE-125"
        }
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      "source": "nvd@nist.gov",
      "type": "Primary"
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      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "type": "Secondary"
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}


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