linux-kernel - [PATCH v2] drm/msm/mdp5: check the return of kzalloc()

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Date:   Thu,  7 Apr 2022 10:31:51 +0800
From:   xkernel.wang@...mail.com
To:     robdclark@...il.com, quic_abhinavk@...cinc.com
Cc:     sean@...rly.run, airlied@...ux.ie, daniel@...ll.ch,
        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 v2] 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.

Besides, since mdp5_plane_reset() is void type, so we should better
set `plane-state` to NULL after releasing it.

Signed-off-by: Xiaoke Wang <xkernel.wang@...mail.com>
---
ChangeLog:
v1->v2 simplify the patch and update the description.
 drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c b/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c
index c6b69af..50e8542 100644
--- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c
+++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c
@@ -90,7 +90,10 @@ static void mdp5_plane_reset(struct drm_plane *plane)
 		__drm_atomic_helper_plane_destroy_state(plane->state);
 
 	kfree(to_mdp5_plane_state(plane->state));
+	plane->state = NULL;
 	mdp5_state = kzalloc(sizeof(*mdp5_state), GFP_KERNEL);
+	if (!mdp5_state)
+		return;
 
 	if (plane->type == DRM_PLANE_TYPE_PRIMARY)
 		mdp5_state->base.zpos = STAGE_BASE;
--