CVE-2026-80789 (GCVE-0-2026-80789)
Vulnerability from cvelistv5
Published
2026-09-04 15:13
Modified
2026-09-04 15:13
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: nvmet-tcp: bound SGL data length before allocating command buffers nvmet_tcp_map_data() reads the host-controlled 32-bit sgl->length and, for the in-capsule offset descriptor (type 0x01), checks it against port->inline_data_size before use. Any other SGL descriptor type -- including the non-inline transport SGL data-block descriptor (type (NVME_TRANSPORT_SGL_DATA_DESC << 4) | NVME_SGL_FMT_TRANSPORT_A, the type a real host uses for out-of-capsule writes) skips that check entirely and falls straight through to: cmd->req.sg = sgl_alloc(len, GFP_KERNEL, &cmd->req.sg_cnt); with len taken directly from the wire, unbounded up to 4 GiB. nvmet_req_init() only parses the command and never inspects sgl->length, and nvmet_check_transfer_len() -- the only other place transfer_len is validated -- runs later, from req->execute(), after the allocation has already happened. For a write command the target responds with an R2T and parks the command waiting for the host to send the data; if the host (or an unauthenticated peer that simply never follows up) never does, the sgl_alloc() buffer stays resident for the life of the command. NVMe/TCP has no mandatory authentication in the default configuration, so any peer able to reach the target portal and complete a Fabrics connect can drive this with a single crafted command, repeatable across queues and connections for amplification. This is unbounded kernel memory allocation triggered by a remote, effectively unauthenticated peer. Validate len against the same NVMET_TCP_MAXH2CDATA ceiling this file already uses to bound per-PDU H2C data, for every SGL descriptor type, before doing any allocation. This closes the gap for the non-inline descriptor while leaving the existing, tighter inline_data_size check in place for the in-capsule case. Runtime-verified on a v6.19 KASAN stand: with this bound in place, a crafted write command carrying an oversized non-inline SGL length is rejected before sgl_alloc() runs, where the same request previously drove an unbounded ~256 MiB kernel allocation (up to 4 GiB) that stayed resident pending an R2T the host never satisfies.
References
Impacted products
Vendor Product Version
Linux Linux Version: 872d26a391da92ed8f0c0f5cb5fef428067b7f30
Version: 872d26a391da92ed8f0c0f5cb5fef428067b7f30
Version: 872d26a391da92ed8f0c0f5cb5fef428067b7f30
Version: 872d26a391da92ed8f0c0f5cb5fef428067b7f30
Version: 872d26a391da92ed8f0c0f5cb5fef428067b7f30
Version: 872d26a391da92ed8f0c0f5cb5fef428067b7f30
Version: 872d26a391da92ed8f0c0f5cb5fef428067b7f30
Version: 872d26a391da92ed8f0c0f5cb5fef428067b7f30
Version: 872d26a391da92ed8f0c0f5cb5fef428067b7f30
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{
  "containers": {
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        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/nvme/target/tcp.c"
          ],
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          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
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              "version": "5.15.220",
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              "version": "7.1.11",
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              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
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      ],
      "cpeApplicability": [
        {
          "nodes": [
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              "negate": false,
              "operator": "OR"
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnvmet-tcp: bound SGL data length before allocating command buffers\n\nnvmet_tcp_map_data() reads the host-controlled 32-bit sgl-\u003elength\nand, for the in-capsule offset descriptor (type 0x01), checks it\nagainst port-\u003einline_data_size before use. Any other SGL descriptor\ntype -- including the non-inline transport SGL data-block descriptor\n(type (NVME_TRANSPORT_SGL_DATA_DESC \u003c\u003c 4) | NVME_SGL_FMT_TRANSPORT_A,\nthe type a real host uses for out-of-capsule writes) skips that check\nentirely and falls straight through to:\n\n\tcmd-\u003ereq.sg = sgl_alloc(len, GFP_KERNEL, \u0026cmd-\u003ereq.sg_cnt);\n\nwith len taken directly from the wire, unbounded up to 4 GiB.\n\nnvmet_req_init() only parses the command and never inspects\nsgl-\u003elength, and nvmet_check_transfer_len() -- the only other place\ntransfer_len is validated -- runs later, from req-\u003eexecute(), after\nthe allocation has already happened. For a write command the target\nresponds with an R2T and parks the command waiting for the host to\nsend the data; if the host (or an unauthenticated peer that simply\nnever follows up) never does, the sgl_alloc() buffer stays resident\nfor the life of the command. NVMe/TCP has no mandatory authentication\nin the default configuration, so any peer able to reach the target\nportal and complete a Fabrics connect can drive this with a single\ncrafted command, repeatable across queues and connections for\namplification. This is unbounded kernel memory allocation\ntriggered by a remote, effectively unauthenticated peer.\n\nValidate len against the same NVMET_TCP_MAXH2CDATA ceiling this file\nalready uses to bound per-PDU H2C data, for every SGL descriptor type,\nbefore doing any allocation. This closes the gap for the non-inline\ndescriptor while leaving the existing, tighter inline_data_size check\nin place for the in-capsule case.\n\nRuntime-verified on a v6.19 KASAN stand: with this bound in place, a\ncrafted write command carrying an oversized non-inline SGL length is\nrejected before sgl_alloc() runs, where the same request previously\ndrove an unbounded ~256 MiB kernel allocation (up to 4 GiB) that\nstayed resident pending an R2T the host never satisfies."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-04T15:13:01.161Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/f6e51b09cbaa5f6f6e6a3a9dafa666f76c37aab5"
        },
        {
          "url": "https://git.kernel.org/stable/c/f63e89a0310264264923f84406dea05fe752de62"
        },
        {
          "url": "https://git.kernel.org/stable/c/0952541b153e258b99d39cdb03ea6919fdeb41d0"
        },
        {
          "url": "https://git.kernel.org/stable/c/25ad03d5c0e858c4b63f1e4b6d461d2af1b30b22"
        },
        {
          "url": "https://git.kernel.org/stable/c/d2acc96c528d589f5827cfb90e8e9229dd9d8cb4"
        },
        {
          "url": "https://git.kernel.org/stable/c/6d27199ebe8cb223022150f74be13f154a964474"
        },
        {
          "url": "https://git.kernel.org/stable/c/14dbe37681a6a7e346fc147bb363ec7cca3180a0"
        },
        {
          "url": "https://git.kernel.org/stable/c/d895e66628f939edbb98608f6e033d3d39e6e546"
        },
        {
          "url": "https://git.kernel.org/stable/c/4a3f00262a044e8e15064b1a6860968bf0500bf4"
        }
      ],
      "title": "nvmet-tcp: bound SGL data length before allocating command buffers",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-80789",
    "datePublished": "2026-09-04T15:13:01.161Z",
    "dateReserved": "2026-08-26T14:34:25.793Z",
    "dateUpdated": "2026-09-04T15:13:01.161Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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