{"id":"CVE-2026-80854","title":"usb: gadget: f_tcm: keep port count until LUN teardown completes","summary":"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_unl…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= c52661d60f636d17e26ad834457db333bd1df494 < c494c5562ca69b61a82f566e3b87a445d2c28929","Linux >= c52661d60f636d17e26ad834457db333bd1df494 < c1f359d9a5efed458946063de65ddbeaacc4f165","Linux >= c52661d60f636d17e26ad834457db333bd1df494 < 178f59a0bccd3f66cdfa5184310f31a58b7257c4","Linux >= c52661d60f636d17e26ad834457db333bd1df494 < ad6f0375d2e93a1d8c015463e5e92dfcb26e311b","Linux >= c52661d60f636d17e26ad834457db333bd1df494 < 2efbfd42441d3ef8137aff2d59e9835e1d5ae780","Linux >= c52661d60f636d17e26ad834457db333bd1df494 < 85aa61fedcb4eb13f3dc5db73f6dc359f41f5d95","Linux >= c52661d60f636d17e26ad834457db333bd1df494 < bbd6aa311a9f4dd17822c7557451458d3d2e980b","Linux >= c52661d60f636d17e26ad834457db333bd1df494 < eaa96a8458f54d6cf0954242ab8b1df2a6fccafa","Linux >= c52661d60f636d17e26ad834457db333bd1df494 < c39d0916da47d94909391876c9e5bd429ea7b1b9","Linux 3.5"],"published":"2026-09-04","updated":"2026-10-19","sourceUpdated":"2026-10-19T08:44:48.320Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-80854","references":[{"url":"https://git.kernel.org/stable/c/c494c5562ca69b61a82f566e3b87a445d2c28929"},{"url":"https://git.kernel.org/stable/c/c1f359d9a5efed458946063de65ddbeaacc4f165"},{"url":"https://git.kernel.org/stable/c/178f59a0bccd3f66cdfa5184310f31a58b7257c4"},{"url":"https://git.kernel.org/stable/c/ad6f0375d2e93a1d8c015463e5e92dfcb26e311b"},{"url":"https://git.kernel.org/stable/c/2efbfd42441d3ef8137aff2d59e9835e1d5ae780"},{"url":"https://git.kernel.org/stable/c/85aa61fedcb4eb13f3dc5db73f6dc359f41f5d95"},{"url":"https://git.kernel.org/stable/c/bbd6aa311a9f4dd17822c7557451458d3d2e980b"},{"url":"https://git.kernel.org/stable/c/eaa96a8458f54d6cf0954242ab8b1df2a6fccafa"},{"url":"https://git.kernel.org/stable/c/c39d0916da47d94909391876c9e5bd429ea7b1b9"}],"tags":["cve.org"],"epss":0.00182,"epssPercentile":0.07249,"ingestedAt":"2026-10-19T09:16:01.494Z","slug":"CVE-2026-80854","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= c52661d60f636d17e26ad834457db333bd1df494 < c494c5562ca69b61a82f566e3b87a445d2c28929`\n- `Linux >= c52661d60f636d17e26ad834457db333bd1df494 < c1f359d9a5efed458946063de65ddbeaacc4f165`\n- `Linux >= c52661d60f636d17e26ad834457db333bd1df494 < 178f59a0bccd3f66cdfa5184310f31a58b7257c4`\n- `Linux >= c52661d60f636d17e26ad834457db333bd1df494 < ad6f0375d2e93a1d8c015463e5e92dfcb26e311b`\n- `Linux >= c52661d60f636d17e26ad834457db333bd1df494 < 2efbfd42441d3ef8137aff2d59e9835e1d5ae780`\n- `Linux >= c52661d60f636d17e26ad834457db333bd1df494 < 85aa61fedcb4eb13f3dc5db73f6dc359f41f5d95`\n- `Linux >= c52661d60f636d17e26ad834457db333bd1df494 < bbd6aa311a9f4dd17822c7557451458d3d2e980b`\n- `Linux >= c52661d60f636d17e26ad834457db333bd1df494 < eaa96a8458f54d6cf0954242ab8b1df2a6fccafa`\n- `Linux >= c52661d60f636d17e26ad834457db333bd1df494 < c39d0916da47d94909391876c9e5bd429ea7b1b9`\n- `Linux 3.5`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}