linux-kernel - [PATCH] cxl/mem: return -EFAULT if copy_to

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Date:   Fri, 19 Feb 2021 12:54:38 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Alison Schofield <alison.schofield@...el.com>,
        Ben Widawsky <ben.widawsky@...el.com>
Cc:     Vishal Verma <vishal.l.verma@...el.com>,
        Ira Weiny <ira.weiny@...el.com>,
        Dan Williams <dan.j.williams@...el.com>,
        linux-cxl@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: [PATCH] cxl/mem: return -EFAULT if copy_to_user() fails

The copy_to_user() function returns the number of bytes remaining to be
copied, but we want to return -EFAULT if the copy doesn't complete.

Fixes: b754ffbbc0ee ("cxl/mem: Add basic IOCTL interface")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
---
 drivers/cxl/mem.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
index 8331a2fc7667..d73ab363ad71 100644
--- a/drivers/cxl/mem.c
+++ b/drivers/cxl/mem.c
@@ -745,7 +745,10 @@ static int cxl_send_cmd(struct cxl_memdev *cxlmd,
 	if (rc)
 		return rc;
 
-	return copy_to_user(s, &send, sizeof(send));
+	if (copy_to_user(s, &send, sizeof(send)))
+		return -EFAULT;
+
+	return 0;
 }
 
 static long __cxl_memdev_ioctl(struct cxl_memdev *cxlmd, unsigned int cmd,
-- 
2.30.0