GHSA-GCQ9-MFQ5-GC89

Vulnerability from github – Published: 2026-06-26 21:32 – Updated: 2026-06-28 09:31
VLAI
Details

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

net: enetc: fix NTMP DMA use-after-free issue

The AI-generated review reported a potential DMA use-after-free issue [1]. If netc_xmit_ntmp_cmd() times out and returns an error, the pending command is not explicitly aborted, while ntmp_free_data_mem() unconditionally frees the DMA buffer. If the buffer has already been reallocated elsewhere, this may lead to silent memory corruption. Because the hardware eventually processes the pending command and perform a DMA write of the response to the physical address of the freed buffer.

To resolve this issue, this patch does the following modifications:

  1. Convert cbdr->ring_lock from a spinlock to a mutex

The lock was originally a spinlock in case NTMP operations might be invoked from atomic context. After downstream support for all NTMP tables, no such usage has materialized. A mutex lock is now required because the driver now needs to reclaim used BDs and release associated DMA memory within the lock's context, while dma_free_coherent() might sleep.

  1. Introduce software command BD (struct netc_swcbd)

The hardware write-back overwrites the addr and len fields of the BD, so the driver cannot rely on the hardware BD to free the associated DMA memory. The driver now maintains a software shadow BD storing the DMA buffer pointer, DMA address, and size. And netc_xmit_ntmp_cmd() only reclaims older BDs when the number of used BDs reaches NETC_CBDR_CLEAN_WORK (16). The software BD enables correct DMA memory release. With this, struct ntmp_dma_buf and ntmp_free_data_mem() are no longer needed and are removed.

  1. Require callers to hold ring_lock across netc_xmit_ntmp_cmd()

netc_xmit_ntmp_cmd() releases the ring_lock before the caller finishes consuming the response. At this point, if a concurrent thread submits a new command, it may trigger ntmp_clean_cbdr() and free the DMA buffer while it is still in use. Move ring_lock ownership to the caller to ensure the response buffer cannot be reclaimed prematurely. So the helpers ntmp_select_and_lock_cbdr() and ntmp_unlock_cbdr() are added.

These changes eliminate the DMA use-after-free condition and ensure safe and consistent BD reclamation and DMA buffer lifecycle management.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2026-53300"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-06-26T20:17:23Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: enetc: fix NTMP DMA use-after-free issue\n\nThe AI-generated review reported a potential DMA use-after-free issue\n[1]. If netc_xmit_ntmp_cmd() times out and returns an error, the pending\ncommand is not explicitly aborted, while ntmp_free_data_mem()\nunconditionally frees the DMA buffer. If the buffer has already been\nreallocated elsewhere, this may lead to silent memory corruption. Because\nthe hardware eventually processes the pending command and perform a DMA\nwrite of the response to the physical address of the freed buffer.\n\nTo resolve this issue, this patch does the following modifications:\n\n1. Convert cbdr-\u003ering_lock from a spinlock to a mutex\n\nThe lock was originally a spinlock in case NTMP operations might be\ninvoked from atomic context. After downstream support for all NTMP\ntables, no such usage has materialized. A mutex lock is now required\nbecause the driver now needs to reclaim used BDs and release associated\nDMA memory within the lock\u0027s context, while dma_free_coherent() might\nsleep.\n\n2. Introduce software command BD (struct netc_swcbd)\n\nThe hardware write-back overwrites the addr and len fields of the BD,\nso the driver cannot rely on the hardware BD to free the associated DMA\nmemory. The driver now maintains a software shadow BD storing the DMA\nbuffer pointer, DMA address, and size. And netc_xmit_ntmp_cmd() only\nreclaims older BDs when the number of used BDs reaches\nNETC_CBDR_CLEAN_WORK (16). The software BD enables correct DMA memory\nrelease. With this, struct ntmp_dma_buf and ntmp_free_data_mem() are no\nlonger needed and are removed.\n\n3. Require callers to hold ring_lock across netc_xmit_ntmp_cmd()\n\nnetc_xmit_ntmp_cmd() releases the ring_lock before the caller finishes\nconsuming the response. At this point, if a concurrent thread submits\na new command, it may trigger ntmp_clean_cbdr() and free the DMA buffer\nwhile it is still in use. Move ring_lock ownership to the caller to\nensure the response buffer cannot be reclaimed prematurely. So the\nhelpers ntmp_select_and_lock_cbdr() and ntmp_unlock_cbdr() are added.\n\nThese changes eliminate the DMA use-after-free condition and ensure safe\nand consistent BD reclamation and DMA buffer lifecycle management.",
  "id": "GHSA-gcq9-mfq5-gc89",
  "modified": "2026-06-28T09:31:48Z",
  "published": "2026-06-26T21:32:17Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-53300"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/37c8933064be714ee672b0a0523c2fd045b73b3d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3cade698881eb238f88cbbfec82acc2110440a3f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/655d9ce9b1d3db0aa5271acb5e5101c66bd0d58b"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}


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