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 BF5C96FBF for ; Sat, 4 Oct 2025 00:40:18 +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=1759538418; cv=none; b=a41Ikgiaw4P2h1kseDhBN6nu4O4GOElbucwP54rFNQF3LuH9US2q3Pr+agEmW0Ug/W9wrXLCIeVH77qRDNxH41qBISq917RYOSH2U3s/jp+wDTd1f4alH5EOONps+RldPvuurCNbMQuVSvlLXDuKht2A0XtzHHxC7ED/10E3B6E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759538418; c=relaxed/simple; bh=JL9k4zPLWiGBeu12uUmzFPdAumpC82AaHQ3NYgb1Kzs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Lc9j8pnrCqS/kCcOwusF4eWKjHDza/VDz8rsDCfGZQ1SBOQWSLyaO5+tZMHCbiAvEO58A0qudajQuYP0Nvlwx0Zbbx0wJyWj7Wub+pTR5ZLZjUP1kER4fPKy9RVT3FP2muQ3NEuV2tjJRrXX1bIgJR7pL4x33nPfx46mHXyRFek= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=auHYXwjG; 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="auHYXwjG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DB32DC4CEFB; Sat, 4 Oct 2025 00:40:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1759538418; bh=JL9k4zPLWiGBeu12uUmzFPdAumpC82AaHQ3NYgb1Kzs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=auHYXwjGILJLkE4nwz36bA1NgBfJvub/Ryc349YSow5GRsDuoPCUaesoHn384UWCO id8lECvfhXEbkKOzuz3WWEbYCxI55w9ACxqFVlNXuOtGH/dLhVXzFkPoig4XW1J7z2 +7xaKqhSruMW8h1eKwSMNMN3wvLjSXRd6cbMlTQ5TwTWuziDxoTFXrOlr/D09DB5bL 7Ms8YAN+ieMcAACBFwoyF+eor4nK4Cqct8fWE+9lshulq+t4LvdETfPz1a3NcVYywv 8qvbHu/0iZ6LPBLZbnw4N7yE5ixnXi3YKFp6aL0JTzIOlcG2tn0G7gafqGLdmpCBKD YnOglfi4+Jvsg== From: Sasha Levin To: stable@vger.kernel.org Cc: Duoming Zhou , Hans Verkuil , Sasha Levin Subject: [PATCH 5.4.y 2/2] media: tuner: xc5000: Fix use-after-free in xc5000_release Date: Fri, 3 Oct 2025 20:40:15 -0400 Message-ID: <20251004004015.4039827-2-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251004004015.4039827-1-sashal@kernel.org> References: <2025100341-dime-left-e15f@gregkh> <20251004004015.4039827-1-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 8b939ab84ee77..ea4f1ae4d686e 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