From: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Date: Mon, 14 Aug 2017 21:53:45 +0000 (+0200)
Subject: drm/tegra: Fix NULL deref in debugfs/iova
X-Git-Tag: v4.14-rc1~179^2~20^2~13
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=68d890a3cca5a96a5443972922c84df89f6301e6;p=linux.git

drm/tegra: Fix NULL deref in debugfs/iova

When IOMMU is off, ->mm_lock is not initialized and ->mm is NULL.

Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: Thierry Reding <treding@nvidia.com>
---

diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
index eddea778290f..86b3e1ce0b65 100644
--- a/drivers/gpu/drm/tegra/drm.c
+++ b/drivers/gpu/drm/tegra/drm.c
@@ -1033,9 +1033,11 @@ static int tegra_debugfs_iova(struct seq_file *s, void *data)
 	struct tegra_drm *tegra = drm->dev_private;
 	struct drm_printer p = drm_seq_file_printer(s);
 
-	mutex_lock(&tegra->mm_lock);
-	drm_mm_print(&tegra->mm, &p);
-	mutex_unlock(&tegra->mm_lock);
+	if (tegra->domain) {
+		mutex_lock(&tegra->mm_lock);
+		drm_mm_print(&tegra->mm, &p);
+		mutex_unlock(&tegra->mm_lock);
+	}
 
 	return 0;
 }