Description
In the Linux kernel, the following vulnerability has been resolved:
usb: gadget: f_tcm: keep port count until LUN teardown completes
tcm_usbg_drop_nexus() permits session removal once tpg_port_count
reaches zero. However, usbg_port_unlink() currently decrements that
count from the fabric_pre_unlink() callback, before core_dev_del_lun()
waits for active se_lun references to drain.
If removal of the last LUN races a nexus removal, the latter can observe
a zero port count and call target_remove_session(). This frees
sess_cmd_map while an in-flight struct usbg_cmd, including its work item,
can still be accessed.
Overlapping the last-LUN unlink with nexus removal reproduces this
lifetime violation as a DEBUG_OBJECTS "free active" warning for
usbg_cmd_work, followed by a target-core BUG/Oops.
The generic target-core unlink path has no callback after
core_dev_del_lun() completes. Add an optional fabric_post_unlink()
callback and use it for the f_tcm port count. The count now remains
nonzero until core_dev_del_lun() has finished draining active LUN
references, preventing nexus removal from freeing the session during
command completion.
usb: gadget: f_tcm: keep port count until LUN teardown completes
tcm_usbg_drop_nexus() permits session removal once tpg_port_count
reaches zero. However, usbg_port_unlink() currently decrements that
count from the fabric_pre_unlink() callback, before core_dev_del_lun()
waits for active se_lun references to drain.
If removal of the last LUN races a nexus removal, the latter can observe
a zero port count and call target_remove_session(). This frees
sess_cmd_map while an in-flight struct usbg_cmd, including its work item,
can still be accessed.
Overlapping the last-LUN unlink with nexus removal reproduces this
lifetime violation as a DEBUG_OBJECTS "free active" warning for
usbg_cmd_work, followed by a target-core BUG/Oops.
The generic target-core unlink path has no callback after
core_dev_del_lun() completes. Add an optional fabric_post_unlink()
callback and use it for the f_tcm port count. The count now remains
nonzero until core_dev_del_lun() has finished draining active LUN
references, preventing nexus removal from freeing the session during
command completion.
Published:
2026-09-04
Score:
n/a
EPSS:
n/a
KEV:
No
Impact:
n/a
Action:
n/a
Analysis
Analysis and contextual insights are available on OpenCVE Cloud.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
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| Linux | Linux | affected |
|
No data.
No data.
No data available yet.
Remediation
No vendor fix or workaround currently provided.
Additional remediation guidance may be available on OpenCVE Cloud.
Tracking
Sign in to view the affected projects.
Advisories
No advisories yet.
References
History
Fri, 04 Sep 2026 16:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_tcm: keep port count until LUN teardown completes tcm_usbg_drop_nexus() permits session removal once tpg_port_count reaches zero. However, usbg_port_unlink() currently decrements that count from the fabric_pre_unlink() callback, before core_dev_del_lun() waits for active se_lun references to drain. If removal of the last LUN races a nexus removal, the latter can observe a zero port count and call target_remove_session(). This frees sess_cmd_map while an in-flight struct usbg_cmd, including its work item, can still be accessed. Overlapping the last-LUN unlink with nexus removal reproduces this lifetime violation as a DEBUG_OBJECTS "free active" warning for usbg_cmd_work, followed by a target-core BUG/Oops. The generic target-core unlink path has no callback after core_dev_del_lun() completes. Add an optional fabric_post_unlink() callback and use it for the f_tcm port count. The count now remains nonzero until core_dev_del_lun() has finished draining active LUN references, preventing nexus removal from freeing the session during command completion. | |
| Title | usb: gadget: f_tcm: keep port count until LUN teardown completes | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-04T15:55:06.478Z
Reserved: 2026-08-26T14:34:25.797Z
Link: CVE-2026-80854
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-04T16:18:14.353
Modified: 2026-09-04T16:18:14.353
Link: CVE-2026-80854
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.