CVE-2026-68367
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_thu
CSIRTS triage
- What
- Race condition between delayed set_alt and teardown in USB gadget TCM function.
- Who is affected
- Systems running affected Linux kernel versions with USB gadget support enabled.
- Urgency
- Medium severity; not currently exploited but can cause synchronization issues.
- Action
- Apply kernel patch or update to a fixed version once released.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Low exploitation risk0.18% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 8% of all EPSS-scored CVEs.
Advisory coverage (3)
- unknownDSA-6466-1 linux - security updatedebian · 2026-08-25
- mediumCVE-2026-68367: usb: gadget: f_tcm: synchronize delayed set_alt with teardownmsrc · 2026-08-11
- unknownCVE-2026-68367: In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_tcm: synchr…nvd · 2026-08-10
External references
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