[PATCH] HID: uclogic: fix UAF on inrange_timer at driver unbind

[Doruk Tan Ozturk <doruk@0sec.ai>]

uclogic_remove() drained the in-range emulation timer before calling
hid_hw_stop():

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

The timer is re-armed from uclogic_raw_event_pen() with a 100 ms
timeout on every pen-in-range report via mod_timer(), and its callback
uclogic_inrange_timeout() dereferences drvdata to deliver a synthetic
BTN_TOOL_PEN release.

drvdata is allocated with devm_kzalloc(), so the HID core devm cleanup
frees it once uclogic_remove() returns. Because the timer is drained
before hid_hw_stop(), a pen report still completing inside
hid_hw_stop() can reach uclogic_raw_event_pen() and re-arm the timer
after the drain. devm then frees drvdata and the re-armed timer fires
on freed memory, a UAF read in uclogic_inrange_timeout(). This is a
disconnect race (USB unplug or rmmod).

Fix by mirroring the letsketch fix: call hid_hw_stop() first, which
synchronously kills the URBs that deliver raw_event(), so once it
returns no path can re-arm the timer. timer_shutdown_sync() then
drains any in-flight callback and permanently disables further
mod_timer() calls.

Found by 0sec (https://0sec.ai) using automated source analysis, as an
incomplete-fix twin of commit 46c8beeccd8a ("HID: letsketch: fix UAF on
inrange_timer at driver unbind"); not runtime-reproduced.

Fixes: 01309e29eb95 ("HID: uclogic: Support in-range reporting emulation")
Cc: stable@vger.kernel.org
Assisted-by: 0sec:claude-opus-4-8
Signed-off-by: Doruk Tan Ozturk <doruk@0sec.ai>
---
 drivers/hid/hid-uclogic-core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hid/hid-uclogic-core.c b/drivers/hid/hid-uclogic-core.c
index b73f09d26688..c440013a609f 100644
--- a/drivers/hid/hid-uclogic-core.c
+++ b/drivers/hid/hid-uclogic-core.c
@@ -548,8 +548,8 @@ static void uclogic_remove(struct hid_device *hdev)
 {
 	struct uclogic_drvdata *drvdata = hid_get_drvdata(hdev);
 
-	timer_delete_sync(&drvdata->inrange_timer);
 	hid_hw_stop(hdev);
+	timer_shutdown_sync(&drvdata->inrange_timer);
 	kfree(drvdata->desc_ptr);
 	uclogic_params_cleanup(&drvdata->params);
 }
-- 
2.43.0