FKIE_CVE-2026-31570

Vulnerability from fkie_nvd - Published: 2026-04-24 15:16 - Updated: 2026-04-24 17:51
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: can: gw: fix OOB heap access in cgw_csum_crc8_rel() cgw_csum_crc8_rel() correctly computes bounds-safe indices via calc_idx(): int from = calc_idx(crc8->from_idx, cf->len); int to = calc_idx(crc8->to_idx, cf->len); int res = calc_idx(crc8->result_idx, cf->len); if (from < 0 || to < 0 || res < 0) return; However, the loop and the result write then use the raw s8 fields directly instead of the computed variables: for (i = crc8->from_idx; ...) /* BUG: raw negative index */ cf->data[crc8->result_idx] = ...; /* BUG: raw negative index */ With from_idx = to_idx = result_idx = -64 on a 64-byte CAN FD frame, calc_idx(-64, 64) = 0 so the guard passes, but the loop iterates with i = -64, reading cf->data[-64], and the write goes to cf->data[-64]. This write might end up to 56 (7.0-rc) or 40 (<= 6.19) bytes before the start of the canfd_frame on the heap. The companion function cgw_csum_xor_rel() uses `from`/`to`/`res` correctly throughout; fix cgw_csum_crc8_rel() to match. Confirmed with KASAN on linux-7.0-rc2: BUG: KASAN: slab-out-of-bounds in cgw_csum_crc8_rel+0x515/0x5b0 Read of size 1 at addr ffff8880076619c8 by task poc_cgw_oob/62 To configure the can-gw crc8 checksums CAP_NET_ADMIN is needed.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/54ecdf76a55e75c1f5085e440f8ab671a3283ef5
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/66b689efd08227da2c5ca49b58b30a95d23c695a
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/84f8b76d24273175a22713e83e90874e1880d801
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/999ca48d55a8a46da21519db7e834e5867200379
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a025283d7f7404c739225e457fb99db2368bb544
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/b9c310d72783cc2f30d103eed83920a5a29c671a
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/c4e8eaa75fa0b6bcbfa5356d6195c4ad0e05e57a
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e7c99348b0612b2bc02d5ce6ff9873261cc7605f
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{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncan: gw: fix OOB heap access in cgw_csum_crc8_rel()\n\ncgw_csum_crc8_rel() correctly computes bounds-safe indices via calc_idx():\n\n    int from = calc_idx(crc8-\u003efrom_idx, cf-\u003elen);\n    int to   = calc_idx(crc8-\u003eto_idx,   cf-\u003elen);\n    int res  = calc_idx(crc8-\u003eresult_idx, cf-\u003elen);\n\n    if (from \u003c 0 || to \u003c 0 || res \u003c 0)\n        return;\n\nHowever, the loop and the result write then use the raw s8 fields directly\ninstead of the computed variables:\n\n    for (i = crc8-\u003efrom_idx; ...)        /* BUG: raw negative index */\n    cf-\u003edata[crc8-\u003eresult_idx] = ...;    /* BUG: raw negative index */\n\nWith from_idx = to_idx = result_idx = -64 on a 64-byte CAN FD frame,\ncalc_idx(-64, 64) = 0 so the guard passes, but the loop iterates with\ni = -64, reading cf-\u003edata[-64], and the write goes to cf-\u003edata[-64].\nThis write might end up to 56 (7.0-rc) or 40 (\u003c= 6.19) bytes before the\nstart of the canfd_frame on the heap.\n\nThe companion function cgw_csum_xor_rel() uses `from`/`to`/`res`\ncorrectly throughout; fix cgw_csum_crc8_rel() to match.\n\nConfirmed with KASAN on linux-7.0-rc2:\n  BUG: KASAN: slab-out-of-bounds in cgw_csum_crc8_rel+0x515/0x5b0\n  Read of size 1 at addr ffff8880076619c8 by task poc_cgw_oob/62\n\nTo configure the can-gw crc8 checksums CAP_NET_ADMIN is needed."
    }
  ],
  "id": "CVE-2026-31570",
  "lastModified": "2026-04-24T17:51:40.810",
  "metrics": {},
  "published": "2026-04-24T15:16:31.520",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/54ecdf76a55e75c1f5085e440f8ab671a3283ef5"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/66b689efd08227da2c5ca49b58b30a95d23c695a"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/84f8b76d24273175a22713e83e90874e1880d801"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/999ca48d55a8a46da21519db7e834e5867200379"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a025283d7f7404c739225e457fb99db2368bb544"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/b9c310d72783cc2f30d103eed83920a5a29c671a"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/c4e8eaa75fa0b6bcbfa5356d6195c4ad0e05e57a"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/e7c99348b0612b2bc02d5ce6ff9873261cc7605f"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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