linux-kernel - [PATCH] drm/nouveau/dispnv04: fix a possible null pointer dereference

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Message-Id: <20231013011850.103967-1-make_ruc2021@163.com>
Date:   Fri, 13 Oct 2023 09:18:50 +0800
From:   Ma Ke <make_ruc2021@....com>
To:     kherbst@...hat.com, lyude@...hat.com, dakr@...hat.com,
        airlied@...il.com, daniel@...ll.ch, tzimmermann@...e.de,
        noralf@...nnes.org, mripard@...nel.org, jani.nikula@...el.com,
        make_ruc2021@....com
Cc:     dri-devel@...ts.freedesktop.org, nouveau@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] drm/nouveau/dispnv04: fix a possible null pointer dereference

In nv17_tv_get_hd_modes(), the return value of drm_mode_duplicate()
is assigned to mode, which will lead to a NULL pointer dereference on
failure of drm_mode_duplicate(). The same applies to drm_cvt_mode().
Add a check to avoid null pointer dereference.

Signed-off-by: Ma Ke <make_ruc2021@....com>
---
 drivers/gpu/drm/nouveau/dispnv04/tvnv17.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/nouveau/dispnv04/tvnv17.c b/drivers/gpu/drm/nouveau/dispnv04/tvnv17.c
index 670c9739e5e1..9c3dc9a5bb46 100644
--- a/drivers/gpu/drm/nouveau/dispnv04/tvnv17.c
+++ b/drivers/gpu/drm/nouveau/dispnv04/tvnv17.c
@@ -258,6 +258,8 @@ static int nv17_tv_get_hd_modes(struct drm_encoder *encoder,
 		if (modes[i].hdisplay == output_mode->hdisplay &&
 		    modes[i].vdisplay == output_mode->vdisplay) {
 			mode = drm_mode_duplicate(encoder->dev, output_mode);
+			if (!mode)
+				continue;
 			mode->type |= DRM_MODE_TYPE_PREFERRED;
 
 		} else {
@@ -265,6 +267,8 @@ static int nv17_tv_get_hd_modes(struct drm_encoder *encoder,
 					    modes[i].vdisplay, 60, false,
 					    (output_mode->flags &
 					     DRM_MODE_FLAG_INTERLACE), false);
+			if (!mode)
+				continue;
 		}
 
 		/* CVT modes are sometimes unsuitable... */
-- 
2.37.2