linux-kernel - [PATCH RESEND] rsxx: Return -EFAULT if copy_to

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Date:   Wed, 3 Mar 2021 13:59:12 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Joshua Morris <josh.h.morris@...ibm.com>,
        Philip Kelleher <pjk1939@...ux.ibm.com>
Cc:     Jens Axboe <axboe@...nel.dk>, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: [PATCH RESEND] rsxx: Return -EFAULT if copy_to_user() fails

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: 36f988e978f8 ("rsxx: Adding in debugfs entries.")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
---
I sent this last June as part of a 2 patch series.  No one responded
to the patches.  The first patch was a NULL derefence fix but I now
think that the correct fix for that is to remove the "enable_blkdev"
module option...  Anyway, this patch is uncontroversial so I'm going to
resend it.

 drivers/block/rsxx/core.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/block/rsxx/core.c b/drivers/block/rsxx/core.c
index 6207449fa716f..558fa263acbc0 100644
--- a/drivers/block/rsxx/core.c
+++ b/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;
-- 
2.26.2