linux-kernel - [PATCH] drm/msm/mdp5: check the return of kzalloc()

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Message-ID: <tencent_F71D40EE9851737338A6289EC3A3942EFE09@qq.com>
Date:   Thu, 24 Mar 2022 16:36:44 +0800
From:   xkernel.wang@...mail.com
To:     robdclark@...il.com, sean@...rly.run, airlied@...ux.ie,
        daniel@...ll.ch
Cc:     linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Xiaoke Wang <xkernel.wang@...mail.com>
Subject: [PATCH] drm/msm/mdp5: check the return of kzalloc()

From: Xiaoke Wang <xkernel.wang@...mail.com>

kzalloc() is a memory allocation function which can return NULL when
some internal memory errors happen. So it is better to check it to
prevent potential wrong memory access.

Signed-off-by: Xiaoke Wang <xkernel.wang@...mail.com>
---
 drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c b/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c
index c6b69af..5f914cc 100644
--- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c
+++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c
@@ -90,15 +90,18 @@ static void mdp5_plane_reset(struct drm_plane *plane)
 		__drm_atomic_helper_plane_destroy_state(plane->state);
 
 	kfree(to_mdp5_plane_state(plane->state));
-	mdp5_state = kzalloc(sizeof(*mdp5_state), GFP_KERNEL);
+	plane->state = NULL;
 
-	if (plane->type == DRM_PLANE_TYPE_PRIMARY)
-		mdp5_state->base.zpos = STAGE_BASE;
-	else
-		mdp5_state->base.zpos = STAGE0 + drm_plane_index(plane);
-	mdp5_state->base.normalized_zpos = mdp5_state->base.zpos;
+	mdp5_state = kzalloc(sizeof(*mdp5_state), GFP_KERNEL);
+	if (mdp5_state) {
+		if (plane->type == DRM_PLANE_TYPE_PRIMARY)
+			mdp5_state->base.zpos = STAGE_BASE;
+		else
+			mdp5_state->base.zpos = STAGE0 + drm_plane_index(plane);
+		mdp5_state->base.normalized_zpos = mdp5_state->base.zpos;
 
-	__drm_atomic_helper_plane_reset(plane, &mdp5_state->base);
+		__drm_atomic_helper_plane_reset(plane, &mdp5_state->base);
+	}
 }
 
 static struct drm_plane_state *
--