From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev,
	Jeongjun Park <aha310510@gmail.com>,
	Inki Dae <inki.dae@samsung.com>
Subject: [PATCH 6.1 388/481] drm/exynos: vidi: fix to avoid directly dereferencing user pointer
Date: Mon, 23 Mar 2026 14:46:10 +0100
Message-ID: <20260323134534.604035907@linuxfoundation.org>
In-Reply-To: <20260323134525.256603107@linuxfoundation.org>
References: <20260323134525.256603107@linuxfoundation.org>
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6.1-stable review patch.  If anyone has any objections, please let me know.

------------------

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 |   15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

--- a/drivers/gpu/drm/exynos/exynos_drm_vidi.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_vidi.c
@@ -252,19 +252,26 @@ int vidi_connection_ioctl(struct drm_dev
 
 	if (vidi->connection) {
 		struct edid *raw_edid;
+		struct edid edid_buf;
+		void *edid_userptr = u64_to_user_ptr(vidi->edid);
 
-		raw_edid = (struct edid *)(unsigned long)vidi->edid;
-		if (!drm_edid_is_valid(raw_edid)) {
+		if (copy_from_user(&edid_buf, edid_userptr, sizeof(struct edid)))
+			return -EFAULT;
+
+		if (!drm_edid_is_valid(&edid_buf)) {
 			DRM_DEV_DEBUG_KMS(ctx->dev,
 					  "edid data is invalid.\n");
 			return -EINVAL;
 		}
-		ctx->raw_edid = drm_edid_duplicate(raw_edid);
-		if (!ctx->raw_edid) {
+
+		raw_edid = drm_edid_duplicate(&edid_buf);
+
+		if (!raw_edid) {
 			DRM_DEV_DEBUG_KMS(ctx->dev,
 					  "failed to allocate raw_edid.\n");
 			return -ENOMEM;
 		}
+		ctx->raw_edid = raw_edid;
 	} else {
 		/*
 		 * with connection = 0, free raw_edid