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([121.185.186.233]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7722a4e27d1sm13140645b3a.81.2025.09.02.04.21.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 Sep 2025 04:21:39 -0700 (PDT) From: Jeongjun Park To: inki.dae@samsung.com, sw0312.kim@samsung.com, kyungmin.park@samsung.com, airlied@gmail.com, simona@ffwll.ch Cc: krzk@kernel.org, alim.akhtar@samsung.com, dri-devel@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, aha310510@gmail.com Subject: [PATCH 1/3] drm/exynos: vidi: use priv->vidi_dev for ctx lookup in vidi_connection_ioctl() Date: Tue, 2 Sep 2025 20:20:41 +0900 Message-Id: <20250902112043.3525123-2-aha310510@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250902112043.3525123-1-aha310510@gmail.com> References: <20250902112043.3525123-1-aha310510@gmail.com> 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 Content-Type: text/plain; charset="utf-8" vidi_connection_ioctl() retrieves the driver_data from drm_dev->dev to obtain a struct vidi_context pointer. However, drm_dev->dev is the exynos-drm master device, and the driver_data contained therein is not the vidi component device, but a completely different device. This can lead to various bugs, ranging from null pointer dereferences and garbage value accesses to, in unlucky cases, out-of-bounds errors, use-after-free errors, and more. To resolve this issue, we need to store/delete the vidi device pointer in exynos_drm_private->vidi_dev during bind/unbind, and then read this exynos_drm_private->vidi_dev within ioctl() to obtain the correct struct vidi_context pointer. Cc: Signed-off-by: Jeongjun Park --- drivers/gpu/drm/exynos/exynos_drm_drv.h | 1 + drivers/gpu/drm/exynos/exynos_drm_vidi.c | 14 +++++++++++++- 2 files changed, 14 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/exynos/exynos_drm_drv.h b/drivers/gpu/drm/exyn= os/exynos_drm_drv.h index 23646e55f142..06c29ff2aac0 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_drv.h +++ b/drivers/gpu/drm/exynos/exynos_drm_drv.h @@ -199,6 +199,7 @@ struct drm_exynos_file_private { struct exynos_drm_private { struct device *g2d_dev; struct device *dma_dev; + struct device *vidi_dev; void *mapping; =20 /* for atomic commit */ diff --git a/drivers/gpu/drm/exynos/exynos_drm_vidi.c b/drivers/gpu/drm/exy= nos/exynos_drm_vidi.c index e094b8bbc0f1..1fe297d512e7 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_vidi.c +++ b/drivers/gpu/drm/exynos/exynos_drm_vidi.c @@ -223,9 +223,14 @@ ATTRIBUTE_GROUPS(vidi); int vidi_connection_ioctl(struct drm_device *drm_dev, void *data, struct drm_file *file_priv) { - struct vidi_context *ctx =3D dev_get_drvdata(drm_dev->dev); + struct exynos_drm_private *priv =3D drm_dev->dev_private; + struct device *dev =3D priv ? priv->vidi_dev : NULL; + struct vidi_context *ctx =3D dev ? dev_get_drvdata(dev) : NULL; struct drm_exynos_vidi_connection *vidi =3D data; =20 + if (!ctx) + return -ENODEV; + if (!vidi) { DRM_DEV_DEBUG_KMS(ctx->dev, "user data for vidi is null.\n"); @@ -371,6 +376,7 @@ static int vidi_bind(struct device *dev, struct device = *master, void *data) { struct vidi_context *ctx =3D dev_get_drvdata(dev); struct drm_device *drm_dev =3D data; + struct exynos_drm_private *priv =3D drm_dev->dev_private; struct drm_encoder *encoder =3D &ctx->encoder; struct exynos_drm_plane *exynos_plane; struct exynos_drm_plane_config plane_config =3D { 0 }; @@ -378,6 +384,8 @@ static int vidi_bind(struct device *dev, struct device = *master, void *data) int ret; =20 ctx->drm_dev =3D drm_dev; + if (priv) + priv->vidi_dev =3D dev; =20 plane_config.pixel_formats =3D formats; plane_config.num_pixel_formats =3D ARRAY_SIZE(formats); @@ -423,8 +431,12 @@ static int vidi_bind(struct device *dev, struct device= *master, void *data) static void vidi_unbind(struct device *dev, struct device *master, void *d= ata) { struct vidi_context *ctx =3D dev_get_drvdata(dev); + struct drm_device *drm_dev =3D data; + struct exynos_drm_private *priv =3D drm_dev->dev_private; =20 timer_delete_sync(&ctx->timer); + if (priv) + priv->vidi_dev =3D NULL; } =20 static const struct component_ops vidi_component_ops =3D { --