[PATCH 6.12 095/265] drm/exynos: vidi: fix to avoid directly dereferencing user pointer

Greg Kroah-Hartman
2026-03-12T20:17:47Z

From: Jeongjun Park <aha310510@gmail.com>

[ Upstream commit d4c98c077c7fb2dfdece7d605e694b5ea2665085 ]

In vidi_connection_ioctl(), vidi->edid(user pointer) is directly
dereferenced in the kernel.

This allows arbitrary kernel memory access from the user space, so instead
of directly accessing the user pointer in the kernel, we should modify it
to copy edid to kernel memory using copy_from_user() and use it.

Cc: <stable@vger.kernel.org>
Signed-off-by: Jeongjun Park <aha310510@gmail.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/exynos/exynos_drm_vidi.c | 22 ++++++++++++++++++----
1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/exynos/exynos_drm_vidi.c b/drivers/gpu/drm/exynos/exynos_drm_vidi.c
index 6de0cced6c9d2..007fd8dad3559 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_vidi.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_vidi.c
@@ -246,13 +246,27 @@ int vidi_connection_ioctl(struct drm_device *drm_dev, void *data,

if (vidi->connection) {
const struct drm_edid *drm_edid;
- const struct edid *raw_edid;
+ const void __user *edid_userptr = u64_to_user_ptr(vidi->edid);
+ void *edid_buf;
+ struct edid hdr;
size_t size;

- raw_edid = (const struct edid *)(unsigned long)vidi->edid;
- size = (raw_edid->extensions + 1) * EDID_LENGTH;
+ if (copy_from_user(&hdr, edid_userptr, sizeof(hdr)))
+ return -EFAULT;

- drm_edid = drm_edid_alloc(raw_edid, size);
+ size = (hdr.extensions + 1) * EDID_LENGTH;
+
+ edid_buf = kmalloc(size, GFP_KERNEL);
+ if (!edid_buf)
+ return -ENOMEM;
+
+ if (copy_from_user(edid_buf, edid_userptr, size)) {
+ kfree(edid_buf);
+ return -EFAULT;
+ }
+
+ drm_edid = drm_edid_alloc(edid_buf, size);
+ kfree(edid_buf);
if (!drm_edid)
return -ENOMEM;

--
2.51.0