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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, Dan Carpenter <dan.carpenter@oracle.com>,
        Sean Paul <seanpaul@chromium.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.1 079/138] drm: return -EFAULT if copy_to_user() fails
Date:   Fri, 12 Jul 2019 14:19:03 +0200
Message-Id: <20190712121631.751652291@linuxfoundation.org>
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[ 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@oracle.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190618131843.GA29463@mwanda
Signed-off-by: Sasha Levin <sashal@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 e407adb033e7..4fbc34425570 100644
--- a/drivers/gpu/drm/drm_bufs.c
+++ b/drivers/gpu/drm/drm_bufs.c
@@ -1332,7 +1332,10 @@ 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 0e3043e08c69..f8672238d444 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