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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Rob Clark <robdclark@gmail.com>,
        linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org,
        freedreno@lists.freedesktop.org,
        Emil Velikov <emil.velikov@collabora.com>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.16 059/279] drm/msm: dont deref error pointer in the msm_fbdev_create error path
Date:   Mon, 18 Jun 2018 10:10:44 +0200
Message-Id: <20180618080611.274697870@linuxfoundation.org>
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4.16-stable review patch.  If anyone has any objections, please let me know.

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

From: Emil Velikov <emil.velikov@collabora.com>

[ Upstream commit 789d4c300e10eb2096ee83c3497118e67ccc951e ]

Currently the error pointer returned by msm_alloc_stolen_fb gets passed
to drm_framebuffer_remove. The latter handles only NULL pointers, thus
a nasty crash will occur.

Drop the unnecessary fail label and the associated checks - both err and
fb will be set at this stage.

Cc: Rob Clark <robdclark@gmail.com>
Cc: linux-arm-msm@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: freedreno@lists.freedesktop.org
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Signed-off-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/gpu/drm/msm/msm_fbdev.c |   11 ++---------
 1 file changed, 2 insertions(+), 9 deletions(-)

--- a/drivers/gpu/drm/msm/msm_fbdev.c
+++ b/drivers/gpu/drm/msm/msm_fbdev.c
@@ -92,8 +92,7 @@ static int msm_fbdev_create(struct drm_f
 
 	if (IS_ERR(fb)) {
 		dev_err(dev->dev, "failed to allocate fb\n");
-		ret = PTR_ERR(fb);
-		goto fail;
+		return PTR_ERR(fb);
 	}
 
 	bo = msm_framebuffer_bo(fb, 0);
@@ -151,13 +150,7 @@ static int msm_fbdev_create(struct drm_f
 
 fail_unlock:
 	mutex_unlock(&dev->struct_mutex);
-fail:
-
-	if (ret) {
-		if (fb)
-			drm_framebuffer_remove(fb);
-	}
-
+	drm_framebuffer_remove(fb);
 	return ret;
 }