From nobody Mon Oct 6 19:04:39 2025 Received: from cstnet.cn (smtp21.cstnet.cn [159.226.251.21]) (using TLSv1.2 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1ACA84A33; Fri, 18 Jul 2025 03:39:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=159.226.251.21 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752810002; cv=none; b=Jg6sahH8ijfJSZzzGy/SH+NyqE83zsAg+HlK1KSw6XNv4jWzU0OGtth3BuuGyr992kNNi+C9J3IOhH4OrsL6Yg3f4i2ABeyLd3pHPDxQVNYUDtnyi+Rn5b50HhSnxurGE8ZwVorkl2YaEB5Dw68VSH2l48NCKvCpwPM3d/Xcvqk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752810002; c=relaxed/simple; bh=4Al64Mz9tQLlIK/bnrwE/T/sj32RszCoH4fQ1R70p2U=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=pj2KALjvCcCmqGuKbOxgWmrkPvnuNKC5+ZnhWYJ8vwM5r8FaVkEyAH63dYVLeuuB36lZZKu5214Dh8PwlUOiYApCv3I2KyCEKlgE+p/CqOxFrsN/w0QrNvyrEe95wTQWmZ5Omw4/R8gsF2E0EZlQRWZ/5HkA/SqSRNOg0o7WGV8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=iscas.ac.cn; spf=pass smtp.mailfrom=iscas.ac.cn; arc=none smtp.client-ip=159.226.251.21 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=iscas.ac.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=iscas.ac.cn Received: from icess-ProLiant-DL380-Gen10.. (unknown [211.71.28.34]) by APP-01 (Coremail) with SMTP id qwCowACnl6tLwHloCD0OBQ--.25172S2; Fri, 18 Jul 2025 11:32:36 +0800 (CST) From: Ma Ke To: chunkuang.hu@kernel.org, p.zabel@pengutronix.de, airlied@gmail.com, simona@ffwll.ch, matthias.bgg@gmail.com, angelogioacchino.delregno@collabora.com, nancy.lin@mediatek.com Cc: akpm@linux-foundation.org, dri-devel@lists.freedesktop.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Ma Ke , stable@vger.kernel.org Subject: [PATCH] drm/mediatek: Fix device/node reference count leaks in mtk_drm_get_all_drm_priv Date: Fri, 18 Jul 2025 11:32:26 +0800 Message-Id: <20250718033226.3390054-1-make24@iscas.ac.cn> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: qwCowACnl6tLwHloCD0OBQ--.25172S2 X-Coremail-Antispam: 1UD129KBjvJXoW7uF1rZFykAFyruw4fGFyDZFb_yoW5JFW7pF 4UGFWFvrW8KF4UKwn5tFW8AF15CF1Iya1fWFyIq343Cw1rZryYk34rt34avrykArWkAF1f JwnxtFy8ur4jkFJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUP014x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26ryj6F1UM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4j 6F4UM28EF7xvwVC2z280aVAFwI0_Cr1j6rxdM28EF7xvwVC2z280aVCY1x0267AKxVWxJr 0_GcWlnxkEFVAIw20F6cxK64vIFxWle2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xv F2IEw4CE5I8CrVC2j2WlYx0E2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r1j6r 4UMcvjeVCFs4IE7xkEbVWUJVW8JwACjcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I 648v4I1lFIxGxcIEc7CjxVA2Y2ka0xkIwI1lc7CjxVAaw2AFwI0_Jw0_GFylc2xSY4AK67 AK6r48MxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAF wI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUtVW8ZwCIc4 0Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AK xVW8JVWxJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Jr0_Gr 1lIxAIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7VUjg4S5UU UUU== X-CM-SenderInfo: ppdnvj2u6l2u1dvotugofq/ Content-Type: text/plain; charset="utf-8" Using device_find_child() and of_find_device_by_node() to locate devices could cause an imbalance in the device's reference count. device_find_child() and of_find_device_by_node() both call get_device() to increment the reference count of the found device before returning the pointer. In mtk_drm_get_all_drm_priv(), these references are never released through put_device(), resulting in permanent reference count increments. Additionally, the for_each_child_of_node() iterator fails to release node references in all code paths. This leaks device node references when loop termination occurs before reaching MAX_CRTC. These reference count leaks may prevent device/node resources from being properly released during driver unbind operations. As comment of device_find_child() says, 'NOTE: you will need to drop the reference with put_device() after use'. Found by code review. Cc: stable@vger.kernel.org Fixes: 1ef7ed48356c ("drm/mediatek: Modify mediatek-drm for mt8195 multi mm= sys support") Signed-off-by: Ma Ke --- drivers/gpu/drm/mediatek/mtk_drm_drv.c | 27 +++++++++++++++++--------- 1 file changed, 18 insertions(+), 9 deletions(-) diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c b/drivers/gpu/drm/media= tek/mtk_drm_drv.c index 7c0c12dde488..c78186debd3e 100644 --- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c +++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c @@ -388,19 +388,24 @@ static bool mtk_drm_get_all_drm_priv(struct device *d= ev) =20 of_id =3D of_match_node(mtk_drm_of_ids, node); if (!of_id) - continue; + goto next; =20 pdev =3D of_find_device_by_node(node); if (!pdev) - continue; + goto next; =20 drm_dev =3D device_find_child(&pdev->dev, NULL, mtk_drm_match); - if (!drm_dev) - continue; + if (!drm_dev) { + put_device(&pdev->dev); + goto next; + } =20 temp_drm_priv =3D dev_get_drvdata(drm_dev); - if (!temp_drm_priv) - continue; + if (!temp_drm_priv) { + put_device(drm_dev); + put_device(&pdev->dev); + goto next; + } =20 if (temp_drm_priv->data->main_len) all_drm_priv[CRTC_MAIN] =3D temp_drm_priv; @@ -412,10 +417,14 @@ static bool mtk_drm_get_all_drm_priv(struct device *d= ev) if (temp_drm_priv->mtk_drm_bound) cnt++; =20 - if (cnt =3D=3D MAX_CRTC) { - of_node_put(node); + put_device(drm_dev); + put_device(&pdev->dev); + +next: + of_node_put(node); + + if (cnt =3D=3D MAX_CRTC) break; - } } =20 if (drm_priv->data->mmsys_dev_num =3D=3D cnt) { --=20 2.25.1