# CVE-2026-68367: usb: gadget: f_tcm: synchronize delayed set_alt with teardown

Status: published. Published: 2026-08-10. Updated: 2026-11-06.

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

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Linux / Linux: ≥ c52661d60f636d17e26ad834457db333bd1df494; < 8fb317058d165c88f3344f59439c14872c162b3c (affected, git); ≥ c52661d60f636d17e26ad834457db333bd1df494; < 90431d8523c0c1c9f8e3e3f0895727063f93da85 (affected, git); ≥ c52661d60f636d17e26ad834457db333bd1df494; < ee07d09419f1c59c74f73107aa08444f2f2fc6c8 (affected, git); ≥ c52661d60f636d17e26ad834457db333bd1df494; < 3118bb872c7dff653294f193d5328a476619e04d (affected, git); ≥ c52661d60f636d17e26ad834457db333bd1df494; < a6eb5a0ae7cd313cfd7df78decd8f43b64c68703 (affected, git); ≥ c52661d60f636d17e26ad834457db333bd1df494; < f282242906c12fd476b86757afba51f211d4f959 (affected, git); ≥ c52661d60f636d17e26ad834457db333bd1df494; < 4c6c6a5588b9a2f8437fb794e852d05fa60ebe53 (affected, git); ≥ c52661d60f636d17e26ad834457db333bd1df494; < 79e2d75725c85607f8a9d87ae9cace62a19f767d (affected, git). Source: CNA: Linux
- Linux / Linux: 3.5 (affected); ≥ 0; < 3.5 (unaffected, semver); ≥ 5.10.266; ≤ 5.10.* (unaffected, semver); ≥ 5.15.217; ≤ 5.15.* (unaffected, semver); ≥ 6.1.184; ≤ 6.1.* (unaffected, semver); ≥ 6.6.151; ≤ 6.6.* (unaffected, semver); ≥ 6.12.103; ≤ 6.12.* (unaffected, semver); ≥ 6.18.42; ≤ 6.18.* (unaffected, semver); ≥ 7.1.6; ≤ 7.1.* (unaffected, semver); ≥ 7.2; ≤ * (unaffected, original_commit_for_fix). Source: CNA: Linux

## Severity and prioritization

- CISA KEV: No listing in collected sources

- EPSS: 0.18% as of 2026-11-06; percentile 8.11%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: Not reported

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://git.kernel.org/stable/c/8fb317058d165c88f3344f59439c14872c162b3c (CNA: Linux)

- https://git.kernel.org/stable/c/90431d8523c0c1c9f8e3e3f0895727063f93da85 (CNA: Linux)

- https://git.kernel.org/stable/c/ee07d09419f1c59c74f73107aa08444f2f2fc6c8 (CNA: Linux)

- https://git.kernel.org/stable/c/3118bb872c7dff653294f193d5328a476619e04d (CNA: Linux)

- https://git.kernel.org/stable/c/a6eb5a0ae7cd313cfd7df78decd8f43b64c68703 (CNA: Linux)

- https://git.kernel.org/stable/c/f282242906c12fd476b86757afba51f211d4f959 (CNA: Linux)

- https://git.kernel.org/stable/c/4c6c6a5588b9a2f8437fb794e852d05fa60ebe53 (CNA: Linux)

- https://git.kernel.org/stable/c/79e2d75725c85607f8a9d87ae9cace62a19f767d (CNA: Linux)

- https://git.kernel.org/stable/c/3118bb872c7dff653294f193d5328a476619e04d (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/4c6c6a5588b9a2f8437fb794e852d05fa60ebe53 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/79e2d75725c85607f8a9d87ae9cace62a19f767d (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/8fb317058d165c88f3344f59439c14872c162b3c (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/90431d8523c0c1c9f8e3e3f0895727063f93da85 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/a6eb5a0ae7cd313cfd7df78decd8f43b64c68703 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/ee07d09419f1c59c74f73107aa08444f2f2fc6c8 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/f282242906c12fd476b86757afba51f211d4f959 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

## Provenance

- CNA: Linux: https://www.cve.org/CVERecord?id=CVE-2026-68367; retrieved 2026-11-06; source updated 2026-11-06

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-68367; retrieved 2026-11-06; source updated 2026-11-06

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-68367; retrieved 2026-11-06; source updated Not reported

Revision: 34313c318d3e4d4f9ad34c358898d42436d7410c4a140bf5295d5583068e4e16

Canonical: https://y2.dev/cve/CVE-2026-68367

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