[PATCH AUTOSEL 4.14 30/35] drm: return -EFAULT if copy_to_user() fails

[Sasha Levin]

From: Dan Carpenter <dan.carpenter at oracle.com>

[ Upstream commit 74b67efa8d7b4f90137f0ab9a80dd319da050350 ]

The copy_from_user() function returns the number of bytes remaining
to be copied but we want to return a negative error code.  Otherwise
the callers treat it as a successful copy.

Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com>
Signed-off-by: Sean Paul <seanpaul at chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190618131843.GA29463@mwanda
Signed-off-by: Sasha Levin <sashal at kernel.org>
---
 drivers/gpu/drm/drm_bufs.c  | 5 ++++-
 drivers/gpu/drm/drm_ioc32.c | 5 ++++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_bufs.c b/drivers/gpu/drm/drm_bufs.c
index 0f05b8d8fefa..b829fde80f7b 100644
--- a/drivers/gpu/drm/drm_bufs.c
+++ b/drivers/gpu/drm/drm_bufs.c
@@ -1321,7 +1321,10 @@ static int copy_one_buf(void *data, int count, struct drm_buf_entry *from)
 				 .size = from->buf_size,
 				 .low_mark = from->low_mark,
 				 .high_mark = from->high_mark};
-	return copy_to_user(to, &v, offsetof(struct drm_buf_desc, flags));
+
+	if (copy_to_user(to, &v, offsetof(struct drm_buf_desc, flags)))
+		return -EFAULT;
+	return 0;
 }
 
 int drm_legacy_infobufs(struct drm_device *dev, void *data,
diff --git a/drivers/gpu/drm/drm_ioc32.c b/drivers/gpu/drm/drm_ioc32.c
index f8e96e648acf..bfeeb6a56135 100644
--- a/drivers/gpu/drm/drm_ioc32.c
+++ b/drivers/gpu/drm/drm_ioc32.c
@@ -372,7 +372,10 @@ static int copy_one_buf32(void *data, int count, struct drm_buf_entry *from)
 			      .size = from->buf_size,
 			      .low_mark = from->low_mark,
 			      .high_mark = from->high_mark};
-	return copy_to_user(to + count, &v, offsetof(drm_buf_desc32_t, flags));
+
+	if (copy_to_user(to + count, &v, offsetof(drm_buf_desc32_t, flags)))
+		return -EFAULT;
+	return 0;
 }
 
 static int drm_legacy_infobufs32(struct drm_device *dev, void *data,
-- 
2.20.1