linux-kernel - [PATCH][V2] drm/nouveau: perform null check on msto[i] rathern than msto

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Date:   Thu, 17 Aug 2017 23:03:23 +0100
From:   Colin King <colin.king@...onical.com>
To:     Ben Skeggs <bskeggs@...hat.com>, David Airlie <airlied@...ux.ie>,
        dri-devel@...ts.freedesktop.org, nouveau@...ts.freedesktop.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH][V2] drm/nouveau: perform null check on msto[i] rathern than msto

From: Colin Ian King <colin.king@...onical.com>

The null check on the array msto is incorrect since msto is never
null. The null check should be instead on msto[i] since this is
being dereferenced in the call to drm_mode_connector_attach_encoder.

Thanks to Emil Velikov for pointing out the mistake in my original
fix and for suggesting the correct fix.

Detected by CoverityScan, CID#1375915 ("Array compared against 0")

Fixes: f479c0ba4a17 ("drm/nouveau/kms/nv50: initial support for DP 1.2 multi-stream")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 drivers/gpu/drm/nouveau/nv50_display.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/nouveau/nv50_display.c b/drivers/gpu/drm/nouveau/nv50_display.c
index f7b4326a4641..ed444ecd9e85 100644
--- a/drivers/gpu/drm/nouveau/nv50_display.c
+++ b/drivers/gpu/drm/nouveau/nv50_display.c
@@ -3141,7 +3141,7 @@ nv50_mstc_new(struct nv50_mstm *mstm, struct drm_dp_mst_port *port,
 	mstc->connector.funcs->reset(&mstc->connector);
 	nouveau_conn_attach_properties(&mstc->connector);
 
-	for (i = 0; i < ARRAY_SIZE(mstm->msto) && mstm->msto; i++)
+	for (i = 0; i < ARRAY_SIZE(mstm->msto) && mstm->msto[i]; i++)
 		drm_mode_connector_attach_encoder(&mstc->connector, &mstm->msto[i]->encoder);
 
 	drm_object_attach_property(&mstc->connector.base, dev->mode_config.path_property, 0);
-- 
2.11.0