From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 C0A53257836 for ; Fri, 3 Oct 2025 20:54:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759524891; cv=none; b=WyT/T7XD4Slh+7oVePYgYrlRrN9wjpWwq8cbBBsPVfDZVuH0I9q2FA1prKEAd+U58sjS2/JTmQNMDyaJie54vPGhesGzbAIZf4OiBHs9NLytB+qgGTTCKvvyPvlW/yb+lIOI6ItP0QqPH5KSunWGQ9YtzKqDAjJllWTnN/YRcec= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759524891; c=relaxed/simple; bh=hF51D3+mOVx4or+38FUJ8pzrNs5XeCs3vLi1r7zW64w=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=VI5k9G4K0IOo4dxH2iQeosLZqk3x3vi/ZheSLru/7ZeBTnwouiS2WRmQ5XVGk0U2+/Qa2/AK4P5rDQmkR9uORuNtid/UDkRXc+BxRZYk6qnGjvPFtOg4ExBtXbFYwIHPHiSyq9damEkN7AoddZbDMn8cBADwQohZ8ei8quUFS5k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dZ60dvUh; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="dZ60dvUh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 17464C4CEFD; Fri, 3 Oct 2025 20:54:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1759524891; bh=hF51D3+mOVx4or+38FUJ8pzrNs5XeCs3vLi1r7zW64w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dZ60dvUhbvrY8dd/sPtC9eJM13X932EsxI1hM2/H3pOdkSNMUSfGWGk47/JnzcMXy YwlszPcYdUPEn0KL+biC9SMKnza7KWPjkMLuGRrgdIgUgAdGRSr+8Q3dxUSnbF03c7 Wis2KvoufQO1qcPRfx8bJeznhvYvL8OoOod4aJzYpsaWwi2WyaC+RI61qaTvaqmXZH JiZOYIBTgnVJxxFcYZLejPpa/2sc2/2jTWG70wnuMF4aK+RyhCVw6wIAu65jVB/nkj ls5fXoIAmcjtU36LzMbtlF70EjPwSiI+0o9vDYOTf1KGuxTNs61vDIzqXMykH9xvla Lm3a/LW8pGEig== From: Sasha Levin To: stable@vger.kernel.org Cc: Duoming Zhou , Hans Verkuil , Sasha Levin Subject: [PATCH 5.15.y 2/2] media: tuner: xc5000: Fix use-after-free in xc5000_release Date: Fri, 3 Oct 2025 16:54:47 -0400 Message-ID: <20251003205447.3385896-2-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251003205447.3385896-1-sashal@kernel.org> References: <2025100340-pleat-amusable-e5dc@gregkh> <20251003205447.3385896-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Duoming Zhou [ Upstream commit 40b7a19f321e65789612ebaca966472055dab48c ] The original code uses cancel_delayed_work() in xc5000_release(), which does not guarantee that the delayed work item timer_sleep has fully completed if it was already running. This leads to use-after-free scenarios where xc5000_release() may free the xc5000_priv while timer_sleep is still active and attempts to dereference the xc5000_priv. A typical race condition is illustrated below: CPU 0 (release thread) | CPU 1 (delayed work callback) xc5000_release() | xc5000_do_timer_sleep() cancel_delayed_work() | hybrid_tuner_release_state(priv) | kfree(priv) | | priv = container_of() // UAF Replace cancel_delayed_work() with cancel_delayed_work_sync() to ensure that the timer_sleep is properly canceled before the xc5000_priv memory is deallocated. A deadlock concern was considered: xc5000_release() is called in a process context and is not holding any locks that the timer_sleep work item might also need. Therefore, the use of the _sync() variant is safe here. This bug was initially identified through static analysis. Fixes: f7a27ff1fb77 ("[media] xc5000: delay tuner sleep to 5 seconds") Cc: stable@vger.kernel.org Signed-off-by: Duoming Zhou Signed-off-by: Hans Verkuil [hverkuil: fix typo in Subject: tunner -> tuner] Signed-off-by: Sasha Levin --- drivers/media/tuners/xc5000.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/media/tuners/xc5000.c b/drivers/media/tuners/xc5000.c index 30aa4ee958bde..ec9a3cd4784e1 100644 --- a/drivers/media/tuners/xc5000.c +++ b/drivers/media/tuners/xc5000.c @@ -1304,7 +1304,7 @@ static void xc5000_release(struct dvb_frontend *fe) mutex_lock(&xc5000_list_mutex); if (priv) { - cancel_delayed_work(&priv->timer_sleep); + cancel_delayed_work_sync(&priv->timer_sleep); hybrid_tuner_release_state(priv); } -- 2.51.0