FKIE_CVE-2026-80854

Vulnerability from fkie_nvd - Published: 2026-09-04 16:18 - Updated: 2026-10-19 09:17
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_tcm: keep port count until LUN teardown completes tcm_usbg_drop_nexus() permits session removal once tpg_port_count reaches zero. However, usbg_port_unlink() currently decrements that count from the fabric_pre_unlink() callback, before core_dev_del_lun() waits for active se_lun references to drain. If removal of the last LUN races a nexus removal, the latter can observe a zero port count and call target_remove_session(). This frees sess_cmd_map while an in-flight struct usbg_cmd, including its work item, can still be accessed. Overlapping the last-LUN unlink with nexus removal reproduces this lifetime violation as a DEBUG_OBJECTS "free active" warning for usbg_cmd_work, followed by a target-core BUG/Oops. The generic target-core unlink path has no callback after core_dev_del_lun() completes. Add an optional fabric_post_unlink() callback and use it for the f_tcm port count. The count now remains nonzero until core_dev_del_lun() has finished draining active LUN references, preventing nexus removal from freeing the session during command completion.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/178f59a0bccd3f66cdfa5184310f31a58b7257c4
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/2efbfd42441d3ef8137aff2d59e9835e1d5ae780
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/85aa61fedcb4eb13f3dc5db73f6dc359f41f5d95
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/ad6f0375d2e93a1d8c015463e5e92dfcb26e311b
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/bbd6aa311a9f4dd17822c7557451458d3d2e980b
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/c1f359d9a5efed458946063de65ddbeaacc4f165
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/c39d0916da47d94909391876c9e5bd429ea7b1b9
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/c494c5562ca69b61a82f566e3b87a445d2c28929
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/eaa96a8458f54d6cf0954242ab8b1df2a6fccafa
Impacted products
Vendor Product Version
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{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/target/target_core_fabric_configfs.c",
            "drivers/usb/gadget/function/f_tcm.c",
            "include/target/target_core_fabric.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "c494c5562ca69b61a82f566e3b87a445d2c28929",
              "status": "affected",
              "version": "c52661d60f636d17e26ad834457db333bd1df494",
              "versionType": "git"
            },
            {
              "lessThan": "c1f359d9a5efed458946063de65ddbeaacc4f165",
              "status": "affected",
              "version": "c52661d60f636d17e26ad834457db333bd1df494",
              "versionType": "git"
            },
            {
              "lessThan": "178f59a0bccd3f66cdfa5184310f31a58b7257c4",
              "status": "affected",
              "version": "c52661d60f636d17e26ad834457db333bd1df494",
              "versionType": "git"
            },
            {
              "lessThan": "ad6f0375d2e93a1d8c015463e5e92dfcb26e311b",
              "status": "affected",
              "version": "c52661d60f636d17e26ad834457db333bd1df494",
              "versionType": "git"
            },
            {
              "lessThan": "2efbfd42441d3ef8137aff2d59e9835e1d5ae780",
              "status": "affected",
              "version": "c52661d60f636d17e26ad834457db333bd1df494",
              "versionType": "git"
            },
            {
              "lessThan": "85aa61fedcb4eb13f3dc5db73f6dc359f41f5d95",
              "status": "affected",
              "version": "c52661d60f636d17e26ad834457db333bd1df494",
              "versionType": "git"
            },
            {
              "lessThan": "bbd6aa311a9f4dd17822c7557451458d3d2e980b",
              "status": "affected",
              "version": "c52661d60f636d17e26ad834457db333bd1df494",
              "versionType": "git"
            },
            {
              "lessThan": "eaa96a8458f54d6cf0954242ab8b1df2a6fccafa",
              "status": "affected",
              "version": "c52661d60f636d17e26ad834457db333bd1df494",
              "versionType": "git"
            },
            {
              "lessThan": "c39d0916da47d94909391876c9e5bd429ea7b1b9",
              "status": "affected",
              "version": "c52661d60f636d17e26ad834457db333bd1df494",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/target/target_core_fabric_configfs.c",
            "drivers/usb/gadget/function/f_tcm.c",
            "include/target/target_core_fabric.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "3.5"
            },
            {
              "lessThan": "3.5",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.269",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.220",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.187",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.156",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.108",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.49",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.13",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.3",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nusb: gadget: f_tcm: keep port count until LUN teardown completes\n\ntcm_usbg_drop_nexus() permits session removal once tpg_port_count\nreaches zero. However, usbg_port_unlink() currently decrements that\ncount from the fabric_pre_unlink() callback, before core_dev_del_lun()\nwaits for active se_lun references to drain.\n\nIf removal of the last LUN races a nexus removal, the latter can observe\na zero port count and call target_remove_session(). This frees\nsess_cmd_map while an in-flight struct usbg_cmd, including its work item,\ncan still be accessed.\n\nOverlapping the last-LUN unlink with nexus removal reproduces this\nlifetime violation as a DEBUG_OBJECTS \"free active\" warning for\nusbg_cmd_work, followed by a target-core BUG/Oops.\n\nThe generic target-core unlink path has no callback after\ncore_dev_del_lun() completes. Add an optional fabric_post_unlink()\ncallback and use it for the f_tcm port count. The count now remains\nnonzero until core_dev_del_lun() has finished draining active LUN\nreferences, preventing nexus removal from freeing the session during\ncommand completion."
    }
  ],
  "id": "CVE-2026-80854",
  "lastModified": "2026-10-19T09:17:21.017",
  "metrics": {},
  "published": "2026-09-04T16:18:14.353",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/178f59a0bccd3f66cdfa5184310f31a58b7257c4"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/2efbfd42441d3ef8137aff2d59e9835e1d5ae780"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/85aa61fedcb4eb13f3dc5db73f6dc359f41f5d95"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/ad6f0375d2e93a1d8c015463e5e92dfcb26e311b"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/bbd6aa311a9f4dd17822c7557451458d3d2e980b"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/c1f359d9a5efed458946063de65ddbeaacc4f165"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/c39d0916da47d94909391876c9e5bd429ea7b1b9"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/c494c5562ca69b61a82f566e3b87a445d2c28929"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/eaa96a8458f54d6cf0954242ab8b1df2a6fccafa"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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