CVE-2026-80766

Summary

In the Linux kernel, the following vulnerability has been resolved:

HID: uclogic: fix use-after-free of inrange_timer on remove

uclogic_remove() cancels the pen in-range timer and then stops the device:

timer_delete_sync(&drvdata->inrange_timer);
hid_hw_stop(hdev);

timer_delete_sync() only guarantees the timer is idle at that instant. uclogic_raw_event_pen() keeps delivering pen reports until hid_hw_stop() stops the transport several lines later, and every report with pen->inrange == UCLOGIC_PARAMS_PEN_INRANGE_NONE re-arms the timer:

mod_timer(&drvdata->inrange_timer, jiffies + msecs_to_jiffies(100));

A report landing between the timer_delete_sync() call and the transport teardown in hid_hw_stop() re-arms inrange_timer after it was cancelled. uclogic_remove() then returns and the devm drvdata is freed, while hid_hw_stop() has already freed the input device drvdata->pen_input points at, so when the timer fires ~100 ms later uclogic_inrange_timeout() dereferences freed memory – a use-after-free in timer-softirq context.

Swapping the two calls is not a fix: stopping the device first frees drvdata->pen_input via hidinput_disconnect() while the timer may still be pending, so a timer already armed before removal fires on the freed input device in the window before timer_delete_sync() runs.

Use timer_shutdown_sync() before hid_hw_stop() instead. It cancels the timer, waits for a running callback while pen_input is still valid, and prevents any further re-arming – a later mod_timer() from an in-flight report is silently ignored – so the timer is provably dead before hid_hw_stop() frees the inputs. This is the ordering the timer core documents for this "timer re-armed from another path" teardown case.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/f40243358b407aec362fe305fabfcdc94a3abd89
• https://git.kernel.org/stable/c/dc5108f18f58870a8dd4203a02a47e571a2be7f0
• https://git.kernel.org/stable/c/9d77ac82e57ead056cf3f71d347083ed9244ad90
• https://git.kernel.org/stable/c/e750cdb6de009aace3c77f37fe2173f96175e8e4
• https://git.kernel.org/stable/c/849e537160bbb77fe419ecc3944bfe125dcd441b
• https://git.kernel.org/stable/c/f1b3ca06380531f49f988f4721d3ed30b0d7a5d2
• https://git.kernel.org/stable/c/f13d0a00204b05e62336da0ab72ea0d87b56690c
• https://git.kernel.org/stable/c/506fd50a9027340f0e9dcc587d10ccb03312dba6

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