CVE-2026-64594
In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_fs: initialize reset_work at allocation time ffs_fs_kill_sb() unconditionally calls cancel_work_sync() on ffs->reset_work when a functionfs instance is unmounted: ffs_data_reset(ffs); cancel_work_sync(&ffs->reset_work); However ffs->reset_work is only ever initialized via INIT_WORK() in ffs_func_set_alt() and ffs_func_disable(), and only on the FFS_DEACTIVATED path. That state is reached solely by ffs_data_closed() when the instance is mounted with the "no_disconnect" option, so for the common case (no "no_disconnect", or mounted and unmounted without ever being deactivated) reset_work is never initialized. ffs_data_new() allocates the ffs_data with kzalloc_obj() and does not initialize reset_work, and ffs_data_reset()/ffs_data_clear() do not touch it either, so reset_work.func is left NULL. cancel_work_sync() on such a work then trips the WARN_ON(!work->func) guard in __flush_work(): WARNING: kernel/workqueue.c:4301 at __flush_work+0x330/0x360, CPU#3: umount Call trace: __flush_work cancel_work_sync ffs_fs_kill_sb [usb_f_fs] deactivate_locked_super deactivate_super cleanup_mnt __cleanup_mnt task_work_run exit_to_user_mode_loop el0_svc On older kernels cancel_work_sync() on a zero-initialized work struct was a silent no-op, which hid the missing initialization. Initialize reset_work once in ffs_data_new() so it is always valid for the lifetime of the ffs_data, and drop the now-redundant INIT_WORK() calls from the two deactivation paths.
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Evidence confidence: Not assessed Evidence-derived, not an exploitability verdict
Severity & attack characteristics
CVSS vector:Not supplied
No CVSS vector is currently available in the source record.
Technical explanation & impact
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Affected products and versions
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Remediation & validation
- Identify exposure by comparing the affected product and version ranges with your asset inventory, SBOM and externally exposed services.
- Review the linked vendor security advisory or patch notes. Upgrade to a vendor-confirmed fixed release; do not infer a fixed version from the CVE description.
- Until patched, consider restricting network access or disabling the affected feature where operationally safe. These are temporary controls, not a substitute for a vendor fix.
- Validate the remediation with a version check and vulnerability rescan, then retain change evidence.
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Vendor advisories, patches & exploit references
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