GHSA-C68P-69WW-4QWM

Vulnerability from github – Published: 2026-08-10 15:33 – Updated: 2026-08-10 15:33
VLAI
Details

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: 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

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

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2026-68367"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-10T13:20:29Z",
    "severity": null
  },
  "details": "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",
  "id": "GHSA-c68p-69ww-4qwm",
  "modified": "2026-08-10T15:33:48Z",
  "published": "2026-08-10T15:33:48Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-68367"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3118bb872c7dff653294f193d5328a476619e04d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4c6c6a5588b9a2f8437fb794e852d05fa60ebe53"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/79e2d75725c85607f8a9d87ae9cace62a19f767d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a6eb5a0ae7cd313cfd7df78decd8f43b64c68703"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f282242906c12fd476b86757afba51f211d4f959"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}



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