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(unknown [211.71.28.34]) by APP-03 (Coremail) with SMTP id rQCowADXZngG65poj7gmCw--.9934S2; Tue, 12 Aug 2025 15:19:45 +0800 (CST) From: Ma Ke To: ck.hu@mediatek.com, 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: dri-devel@lists.freedesktop.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, akpm@linux-foundation.org, Ma Ke , stable@vger.kernel.org Subject: [PATCH v2] drm/mediatek: Fix device/node reference count leaks in mtk_drm_get_all_drm_priv Date: Tue, 12 Aug 2025 15:19:32 +0800 Message-Id: <20250812071932.471730-1-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: rQCowADXZngG65poj7gmCw--.9934S2 X-Coremail-Antispam: 1UD129KBjvJXoWxCr4UCr48XrWDJw1xXw43ZFb_yoW5GryrpF WUGFWFvrW8tr4UKrsYyFW8CF1YkF1xta1fWF1Igw13Cw1rZryay345t34avryDArWkAF1r JwnxtFy8CFyjkFJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBE14x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26ryj6F1UM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4j 6F4UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I0E14v26rxl6s 0DM2vYz4IE04k24VAvwVAKI4IrM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI 64kE6c02F40Ex7xfMcIj6xIIjxv20xvE14v26r106r15McIj6I8E87Iv67AKxVWUJVW8Jw Am72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41lF7I21c0EjII2zVCS5cI20VAG YxC7M4IIrI8v6xkF7I0E8cxan2IY04v7MxkF7I0En4kS14v26r1q6r43MxkIecxEwVAFwV W8CwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v2 6r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_Jw0_GFylIxkGc2 Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAFwI0_ Gr0_Cr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4UMI IF0xvEx4A2jsIEc7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x0JUpa0PUUUUU = 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 Reviewed-by: CK Hu --- Changes in v2: - added goto labels as suggestions. --- drivers/gpu/drm/mediatek/mtk_drm_drv.c | 21 ++++++++++++++------- 1 file changed, 14 insertions(+), 7 deletions(-) diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c b/drivers/gpu/drm/media= tek/mtk_drm_drv.c index d5e6bab36414..f8a817689e16 100644 --- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c +++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c @@ -387,19 +387,19 @@ 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_put_node; =20 pdev =3D of_find_device_by_node(node); if (!pdev) - continue; + goto next_put_node; =20 drm_dev =3D device_find_child(&pdev->dev, NULL, mtk_drm_match); if (!drm_dev) - continue; + goto next_put_device_pdev_dev; =20 temp_drm_priv =3D dev_get_drvdata(drm_dev); if (!temp_drm_priv) - continue; + goto next_put_device_drm_dev; =20 if (temp_drm_priv->data->main_len) all_drm_priv[CRTC_MAIN] =3D temp_drm_priv; @@ -411,10 +411,17 @@ 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); +next_put_device_drm_dev: + put_device(drm_dev); + +next_put_device_pdev_dev: + put_device(&pdev->dev); + +next_put_node: + 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