queue-6.18/drm-exynos-vidi-fix-to-avoid-directly-dereferencing-user-pointer.patch

From d4c98c077c7fb2dfdece7d605e694b5ea2665085 Mon Sep 17 00:00:00 2001
From: Jeongjun Park <aha310510@gmail.com>
Date: Mon, 19 Jan 2026 17:25:52 +0900
Subject: drm/exynos: vidi: fix to avoid directly dereferencing user pointer

From: Jeongjun Park <aha310510@gmail.com>

commit d4c98c077c7fb2dfdece7d605e694b5ea2665085 upstream.

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/gpu/drm/exynos/exynos_drm_vidi.c |   22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

--- a/drivers/gpu/drm/exynos/exynos_drm_vidi.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_vidi.c
@@ -262,13 +262,27 @@ int vidi_connection_ioctl(struct drm_dev
 
 	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;