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 EF6C44086A; Tue, 11 Nov 2025 00:53:33 +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=1762822414; cv=none; b=hYG/baCt4CN/7BQFItbRXGgRZ4ED0S2NXO+QzEM1WCe9j4ewv/oU4i5TRdTz+6WFeENADYNWfMWq+0Ia2nH9wYPNRnMyWI8oT8haA6pBazomNNpnORMZQMhuwD7Dfol5Ubh4DajvDP60udXYpqmQEagm/ChNBEIwqml8OsLhui4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762822414; c=relaxed/simple; bh=ij8VMSVky3d80Oqb/Adv1Q/cz3MyKbwXsOij7wQI73I=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=U6p4qLCX27TzXxJ2RlSP4BPhQkCxpkl/Br57RvL1ExRmATDcgJFHAYXNBkq/Q0qWMJD4592/ADPmA/ywB2PosYIzsgOeeqXB/Yt6Cn+yyPaJZsvGzM/UOk9s11GsU/1X0lcUbw3g66snJcNZ/TWKRkAIbrpvCU05rloErkRi82c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=0MPgjl0h; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="0MPgjl0h" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8FB05C113D0; Tue, 11 Nov 2025 00:53:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1762822413; bh=ij8VMSVky3d80Oqb/Adv1Q/cz3MyKbwXsOij7wQI73I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0MPgjl0hXo2h4wDXXd17rB4Y6LlPvOhSDbKQ1n5bw5PLs7/C+//lM+abjx0D9VAzm yq5YNjpEE7X/Y1S1Mxisog+/LhSgSDw9w7MBCGiMbB9q6cCLGXhG+2EYs8abOFsg6G BmgLsDqr3xBMQHR0yWcJgJT4o0zbKIefLHvz5hpI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sjoerd Simons , Ma Ke , AngeloGioacchino Del Regno , Johan Hovold , Ritesh Raj Sarraf , CK Hu , Chun-Kuang Hu Subject: [PATCH 6.17 103/849] drm/mediatek: Fix device use-after-free on unbind Date: Tue, 11 Nov 2025 09:34:33 +0900 Message-ID: <20251111004538.892936897@linuxfoundation.org> X-Mailer: git-send-email 2.51.2 In-Reply-To: <20251111004536.460310036@linuxfoundation.org> References: <20251111004536.460310036@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.17-stable review patch. If anyone has any objections, please let me know. ------------------ From: Johan Hovold commit 926d002e6d7e2f1fd5c1b53cf6208153ee7d380d upstream. A recent change fixed device reference leaks when looking up drm platform device driver data during bind() but failed to remove a partial fix which had been added by commit 80805b62ea5b ("drm/mediatek: Fix kobject put for component sub-drivers"). This results in a reference imbalance on component bind() failures and on unbind() which could lead to a user-after-free. Make sure to only drop the references after retrieving the driver data by effectively reverting the previous partial fix. Note that holding a reference to a device does not prevent its driver data from going away so there is no point in keeping the reference. Fixes: 1f403699c40f ("drm/mediatek: Fix device/node reference count leaks in mtk_drm_get_all_drm_priv") Reported-by: Sjoerd Simons Closes: https://lore.kernel.org/r/20251003-mtk-drm-refcount-v1-1-3b3f2813b0db@collabora.com Cc: stable@vger.kernel.org Cc: Ma Ke Cc: AngeloGioacchino Del Regno Signed-off-by: Johan Hovold Reviewed-by: AngeloGioacchino Del Regno Reviewed-by: Sjoerd Simons Tested-by: Sjoerd Simons Tested-by: Ritesh Raj Sarraf Reviewed-by: CK Hu Link: https://patchwork.kernel.org/project/dri-devel/patch/20251006093937.27869-1-johan@kernel.org/ Signed-off-by: Chun-Kuang Hu Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/mediatek/mtk_drm_drv.c | 10 ---------- 1 file changed, 10 deletions(-) --- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c +++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c @@ -686,10 +686,6 @@ err_free: for (i = 0; i < private->data->mmsys_dev_num; i++) private->all_drm_private[i]->drm = NULL; err_put_dev: - for (i = 0; i < private->data->mmsys_dev_num; i++) { - /* For device_find_child in mtk_drm_get_all_priv() */ - put_device(private->all_drm_private[i]->dev); - } put_device(private->mutex_dev); return ret; } @@ -697,18 +693,12 @@ err_put_dev: static void mtk_drm_unbind(struct device *dev) { struct mtk_drm_private *private = dev_get_drvdata(dev); - int i; /* for multi mmsys dev, unregister drm dev in mmsys master */ if (private->drm_master) { drm_dev_unregister(private->drm); mtk_drm_kms_deinit(private->drm); drm_dev_put(private->drm); - - for (i = 0; i < private->data->mmsys_dev_num; i++) { - /* For device_find_child in mtk_drm_get_all_priv() */ - put_device(private->all_drm_private[i]->dev); - } put_device(private->mutex_dev); } private->mtk_drm_bound = false;