[PATCH][next] nouveau/svm: Fix missing failure check on call to make_device_exclusive_range

[Colin King <colin.king@xxxxxxxxxxxxx>]

From: Colin Ian King <colin.king@xxxxxxxxxxxxx>

The call to make_device_exclusive_range can potentially fail leaving
pointer page not initialized that leads to an uninitialized pointer
read issue. Fix this by adding a check to see if the call failed and
returning the error code.

Addresses-Coverity: ("Uninitialized pointer read")
Fixes: c620bba9828c ("nouveau/svm: implement atomic SVM access")
Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
---
 drivers/gpu/drm/nouveau/nouveau_svm.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.c b/drivers/gpu/drm/nouveau/nouveau_svm.c
index 84726a89e665..b913b4907088 100644
--- a/drivers/gpu/drm/nouveau/nouveau_svm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_svm.c
@@ -609,8 +609,10 @@ static int nouveau_atomic_range_fault(struct nouveau_svmm *svmm,
 
 		notifier_seq = mmu_interval_read_begin(&notifier->notifier);
 		mmap_read_lock(mm);
-		make_device_exclusive_range(mm, start, start + PAGE_SIZE,
-					    &page, drm->dev);
+		ret = make_device_exclusive_range(mm, start, start + PAGE_SIZE,
+						  &page, drm->dev);
+		if (ret < 0)
+			goto out;
 		mmap_read_unlock(mm);
 		if (!page) {
 			ret = -EINVAL;
-- 
2.31.1