rsxx: Return -EFAULT if copy_to_user() fails

[ Upstream commit 77516d2 ]

The copy_to_user() function returns the number of bytes remaining but
we want to return -EFAULT to the user if it can't complete the copy.
The "st" variable only holds zero on success or negative error codes on
failure so the type should be int.

Fixes: 36f988e ("rsxx: Adding in debugfs entries.")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: Dan Carpenter

drivers/block/rsxx/core.c

@@ -165,15 +165,17 @@ static ssize_t rsxx_cram_read(struct file *fp, char __user *ubuf,
 {
 	struct rsxx_cardinfo *card = file_inode(fp)->i_private;
 	char *buf;
-	ssize_t st;
+	int st;
 
 	buf = kzalloc(cnt, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 
 	st = rsxx_creg_read(card, CREG_ADD_CRAM + (u32)*ppos, cnt, buf, 1);
-	if (!st)
-		st = copy_to_user(ubuf, buf, cnt);
+	if (!st) {
+		if (copy_to_user(ubuf, buf, cnt))
+			st = -EFAULT;
+	}
 	kfree(buf);
 	if (st)
 		return st;