CVE-2026-68367 (GCVE-0-2026-68367)
Vulnerability from cvelistv5
Published
2026-08-10 12:03
Modified
2026-08-23 12:46
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_tcm: synchronize delayed set_alt with teardown The f_tcm set_alt() path defers endpoint setup to a work item and completes the delayed status response from process context. The delayed work uses f_tcm private state and may complete the setup request after disconnect or function teardown has already moved on. Cancel and drain the delayed set_alt work when the function is unbound or freed. For disable paths, which are reached under the composite device lock, use a small state machine and a non-sleeping cancellation path instead of cancel_work_sync(). If the work is already running, mark it cancelled and let the worker own the cleanup; otherwise tcm_disable() can cancel the queued work and clean up immediately. Also serialize the final delayed-status completion with the cancellation check while holding the composite device lock. This prevents a disconnect from clearing delayed_status while the worker is about to complete the control request. Validation reproduced this kernel report: BUG: KASAN: slab-use-after-free in tcm_delayed_set_alt+0x6c/0xef0 Call Trace: <TASK> dump_stack_lvl+0x66/0xa0 print_report+0xce/0x630 ? tcm_delayed_set_alt+0x6c/0xef0 ? srso_alias_return_thunk+0x5/0xfbef5 ? __virt_addr_valid+0x188/0x320 ? tcm_delayed_set_alt+0x6c/0xef0 kasan_report+0xe0/0x110 ? tcm_delayed_set_alt+0x6c/0xef0 tcm_delayed_set_alt+0x6c/0xef0 ? __pfx_tcm_delayed_set_alt+0x10/0x10 ? process_one_work+0x4cb/0xb90 ? rcu_is_watching+0x20/0x50 ? tcm_delayed_set_alt+0x9/0xef0 process_one_work+0x4d7/0xb90 ? __pfx_process_one_work+0x10/0x10 ? srso_alias_return_thunk+0x5/0xfbef5 ? __list_add_valid_or_report+0x37/0xf0 ? __pfx_tcm_delayed_set_alt+0x10/0x10 ? srso_alias_return_thunk+0x5/0xfbef5 worker_thread+0x2d8/0x570 ? __pfx_worker_thread+0x10/0x10 kthread+0x1ad/0x1f0 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x3c9/0x540 ? __pfx_ret_from_fork+0x10/0x10 ? srso_alias_return_thunk+0x5/0xfbef5 ? __switch_to+0x2e9/0x730 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 </TASK> Allocated by task 544: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 __kasan_kmalloc+0x8f/0xa0 tcm_alloc+0x68/0x180 usb_get_function+0x36/0x60 config_usb_cfg_link+0x125/0x1b0 configfs_symlink+0x322/0x890 vfs_symlink+0xc2/0x270 filename_symlinkat+0x295/0x2f0 __x64_sys_symlinkat+0x62/0x90 do_syscall_64+0x115/0x6a0 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 661: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 kasan_save_free_info+0x3b/0x60 __kasan_slab_free+0x43/0x70 kfree+0x2f9/0x530 config_usb_cfg_unlink+0x173/0x1e0 configfs_unlink+0x1fa/0x340 vfs_unlink+0x15c/0x510 filename_unlinkat+0x2ba/0x450 __x64_sys_unlinkat+0x63/0x90 do_syscall_64+0x115/0x6a0 entry_SYSCALL_64_after_hwframe+0x77/0x7f
References
Impacted products
Vendor Product Version
Linux Linux Version: c52661d60f636d17e26ad834457db333bd1df494
Version: c52661d60f636d17e26ad834457db333bd1df494
Version: c52661d60f636d17e26ad834457db333bd1df494
Version: c52661d60f636d17e26ad834457db333bd1df494
Version: c52661d60f636d17e26ad834457db333bd1df494
Version: c52661d60f636d17e26ad834457db333bd1df494
Version: c52661d60f636d17e26ad834457db333bd1df494
Version: c52661d60f636d17e26ad834457db333bd1df494
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/usb/gadget/function/f_tcm.c",
            "drivers/usb/gadget/function/tcm.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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        {
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          "product": "Linux",
          "programFiles": [
            "drivers/usb/gadget/function/f_tcm.c",
            "drivers/usb/gadget/function/tcm.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "status": "affected",
              "version": "3.5"
            },
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
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              "status": "unaffected",
              "version": "5.10.266",
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            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.217",
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            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.184",
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            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.151",
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            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.103",
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            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.42",
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            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
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                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nusb: gadget: f_tcm: synchronize delayed set_alt with teardown\n\nThe f_tcm set_alt() path defers endpoint setup to a work item and\ncompletes the delayed status response from process context. The delayed\nwork uses f_tcm private state and may complete the setup request after\ndisconnect or function teardown has already moved on.\n\nCancel and drain the delayed set_alt work when the function is unbound or\nfreed. For disable paths, which are reached under the composite device\nlock, use a small state machine and a non-sleeping cancellation path\ninstead of cancel_work_sync(). If the work is already running, mark it\ncancelled and let the worker own the cleanup; otherwise tcm_disable() can\ncancel the queued work and clean up immediately.\n\nAlso serialize the final delayed-status completion with the cancellation\ncheck while holding the composite device lock. This prevents a disconnect\nfrom clearing delayed_status while the worker is about to complete the\ncontrol request.\n\nValidation reproduced this kernel report:\nBUG: KASAN: slab-use-after-free in tcm_delayed_set_alt+0x6c/0xef0\n\nCall Trace:\n \u003cTASK\u003e\n dump_stack_lvl+0x66/0xa0\n print_report+0xce/0x630\n ? tcm_delayed_set_alt+0x6c/0xef0\n ? srso_alias_return_thunk+0x5/0xfbef5\n ? __virt_addr_valid+0x188/0x320\n ? tcm_delayed_set_alt+0x6c/0xef0\n kasan_report+0xe0/0x110\n ? tcm_delayed_set_alt+0x6c/0xef0\n tcm_delayed_set_alt+0x6c/0xef0\n ? __pfx_tcm_delayed_set_alt+0x10/0x10\n ? process_one_work+0x4cb/0xb90\n ? rcu_is_watching+0x20/0x50\n ? tcm_delayed_set_alt+0x9/0xef0\n process_one_work+0x4d7/0xb90\n ? __pfx_process_one_work+0x10/0x10\n ? srso_alias_return_thunk+0x5/0xfbef5\n ? __list_add_valid_or_report+0x37/0xf0\n ? __pfx_tcm_delayed_set_alt+0x10/0x10\n ? srso_alias_return_thunk+0x5/0xfbef5\n worker_thread+0x2d8/0x570\n ? __pfx_worker_thread+0x10/0x10\n kthread+0x1ad/0x1f0\n ? __pfx_kthread+0x10/0x10\n ret_from_fork+0x3c9/0x540\n ? __pfx_ret_from_fork+0x10/0x10\n ? srso_alias_return_thunk+0x5/0xfbef5\n ? __switch_to+0x2e9/0x730\n ? __pfx_kthread+0x10/0x10\n ret_from_fork_asm+0x1a/0x30\n \u003c/TASK\u003e\n\nAllocated by task 544:\n kasan_save_stack+0x33/0x60\n kasan_save_track+0x14/0x30\n __kasan_kmalloc+0x8f/0xa0\n tcm_alloc+0x68/0x180\n usb_get_function+0x36/0x60\n config_usb_cfg_link+0x125/0x1b0\n configfs_symlink+0x322/0x890\n vfs_symlink+0xc2/0x270\n filename_symlinkat+0x295/0x2f0\n __x64_sys_symlinkat+0x62/0x90\n do_syscall_64+0x115/0x6a0\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nFreed by task 661:\n kasan_save_stack+0x33/0x60\n kasan_save_track+0x14/0x30\n kasan_save_free_info+0x3b/0x60\n __kasan_slab_free+0x43/0x70\n kfree+0x2f9/0x530\n config_usb_cfg_unlink+0x173/0x1e0\n configfs_unlink+0x1fa/0x340\n vfs_unlink+0x15c/0x510\n filename_unlinkat+0x2ba/0x450\n __x64_sys_unlinkat+0x63/0x90\n do_syscall_64+0x115/0x6a0\n entry_SYSCALL_64_after_hwframe+0x77/0x7f"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-23T12:46:18.779Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/8fb317058d165c88f3344f59439c14872c162b3c"
        },
        {
          "url": "https://git.kernel.org/stable/c/90431d8523c0c1c9f8e3e3f0895727063f93da85"
        },
        {
          "url": "https://git.kernel.org/stable/c/ee07d09419f1c59c74f73107aa08444f2f2fc6c8"
        },
        {
          "url": "https://git.kernel.org/stable/c/3118bb872c7dff653294f193d5328a476619e04d"
        },
        {
          "url": "https://git.kernel.org/stable/c/a6eb5a0ae7cd313cfd7df78decd8f43b64c68703"
        },
        {
          "url": "https://git.kernel.org/stable/c/f282242906c12fd476b86757afba51f211d4f959"
        },
        {
          "url": "https://git.kernel.org/stable/c/4c6c6a5588b9a2f8437fb794e852d05fa60ebe53"
        },
        {
          "url": "https://git.kernel.org/stable/c/79e2d75725c85607f8a9d87ae9cace62a19f767d"
        }
      ],
      "title": "usb: gadget: f_tcm: synchronize delayed set_alt with teardown",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-68367",
    "datePublished": "2026-08-10T12:03:44.600Z",
    "dateReserved": "2026-07-30T09:28:09.385Z",
    "dateUpdated": "2026-08-23T12:46:18.779Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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