From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8ADE6456DE2 for ; Wed, 26 Aug 2026 17:47:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787766484; cv=none; b=OBBGh5G3OaA+cKwGz0Zistpx2Zh2i1mCdLzZdk5itPtwO1XJ2xp5QSDzhclnXs44Gdqh2ErcwBCIH6ik23lTQlP3lX2nw06fPmakvHJN9bNi8ooKfZag/0qM/J+6EUqo+ET6oGtZvxp4aYbU1IhWGrudQ7O4/sanCqsqEK1pifQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787766484; c=relaxed/simple; bh=DA40hXqCrOE9QuOODMnONXHh6GRpfBwCXHYwq/5b+lE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=TuUupJrxaxTFQjshX565cS1ujFtJLEeKs0KQRTHYjv0x7ZI8a0WopLPj5+EnxJnJqJyLqXWN4SazRjHZTRn5gQRip45fy201vNqBqIR4wwEQTz2pUnZTjhukOMUfeM9+OCPWWvCZCLyABxUSjjQM80Mlmjz46hb2omFkS+Id+T0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=f6tTtqPv; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="f6tTtqPv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5BFE91F000E9; Wed, 26 Aug 2026 17:47:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787766467; bh=ns94IZ8IqPCA2ixUkD83nWOTtKg61RIi99qKLrDX90A=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=f6tTtqPv/8nWsXFpu8yl3m8oZfyX3cAkmlRxNl3Ee/4Aex7zaO4vQRbLfQT4GChkg WmNjjzQQdo9tDWWIelUKioqLvfhL9Cg4LnsJ1sfa3mlV6rbd5wDxCq0K6zjRz9b5oe r/VkzPZXtwapRxXlg7CBjMstMjOsIi6qhmg/Q8bLB2q2AY5B3V7dNqN9w7tooK79h7 k1KCb5V8lifU9TqfMy0wrRxboymvCO64yR60P2tLAoqOMckeXk9ruMlXVss4zrc2Ij WugnU4iHrbs9ebI+1qrIdG2gi/mFJKEPdAkpv08eSABg2hr1LXI7s3YRoknfYUjNTS 8cjDhS42vRk+w== From: Sasha Levin To: stable@vger.kernel.org Cc: Ibrahim Hashimov , Jiri Kosina , Sasha Levin Subject: [PATCH 5.15.y] HID: uclogic: fix use-after-free of inrange_timer on remove Date: Wed, 26 Aug 2026 13:47:45 -0400 Message-ID: <20260826174745.2488760-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026082557-kindling-coping-1767@gregkh> References: <2026082557-kindling-coping-1767@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Ibrahim Hashimov [ Upstream commit 506fd50a9027340f0e9dcc587d10ccb03312dba6 ] 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. Fixes: 01309e29eb95 ("HID: uclogic: Support in-range reporting emulation") Cc: stable@vger.kernel.org Signed-off-by: Ibrahim Hashimov Assisted-by: AuditCode-AI:2026.07 Signed-off-by: Jiri Kosina [ changed timer_delete_sync() to del_timer_sync() in the removed line to match the pre-rename API on this branch ] Signed-off-by: Sasha Levin --- drivers/hid/hid-uclogic-core.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/drivers/hid/hid-uclogic-core.c b/drivers/hid/hid-uclogic-core.c index 340f92cfc812e..5cc0742ac38b3 100644 --- a/drivers/hid/hid-uclogic-core.c +++ b/drivers/hid/hid-uclogic-core.c @@ -346,7 +346,17 @@ static void uclogic_remove(struct hid_device *hdev) { struct uclogic_drvdata *drvdata = hid_get_drvdata(hdev); - del_timer_sync(&drvdata->inrange_timer); + /* + * Shut the in-range timer down before stopping the device. + * uclogic_raw_event_pen() re-arms inrange_timer on every pen report + * and keeps running until hid_hw_stop() stops the transport, so a + * plain timer_delete_sync() here can be undone by a report landing in + * the window before hid_hw_stop(). timer_shutdown_sync() cancels the + * timer and makes any later re-arm a no-op, so it is provably dead + * before hid_hw_stop() frees the input device drvdata->pen_input + * points at. + */ + timer_shutdown_sync(&drvdata->inrange_timer); hid_hw_stop(hdev); kfree(drvdata->desc_ptr); uclogic_params_cleanup(&drvdata->params); -- 2.53.0