linux-kernel - [PATCH] media: dvb_ringbuffer: Return -EFAULT if copy fails

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Date:   Wed, 24 May 2023 09:27:33 +0800
From:   Su Hui <suhui@...china.com>
To:     Mauro Carvalho Chehab <mchehab@...nel.org>
Cc:     YongSu Yoo <yongsuyoo0215@...il.com>, linux-media@...r.kernel.org,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        Su Hui <suhui@...china.com>
Subject: [PATCH] media: dvb_ringbuffer: Return -EFAULT if copy fails

The copy_to/from_user() functions return the number of bytes remaining
to be copied, but we want to return -EFAULT to the user.

Fixes: 04da2daee383 ("[media] ngene: properly handle __user ptr")
Signed-off-by: Su Hui <suhui@...china.com>
---
 drivers/media/dvb-core/dvb_ringbuffer.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/media/dvb-core/dvb_ringbuffer.c b/drivers/media/dvb-core/dvb_ringbuffer.c
index 7d4558de8e83..f132578840ad 100644
--- a/drivers/media/dvb-core/dvb_ringbuffer.c
+++ b/drivers/media/dvb-core/dvb_ringbuffer.c
@@ -216,7 +216,7 @@ ssize_t dvb_ringbuffer_write_user(struct dvb_ringbuffer *rbuf,
 	if (split > 0) {
 		status = copy_from_user(rbuf->data+rbuf->pwrite, buf, split);
 		if (status)
-			return len - todo;
+			return -EFAULT;
 		buf += split;
 		todo -= split;
 		/* smp_store_release() for write pointer update to ensure that
@@ -228,7 +228,7 @@ ssize_t dvb_ringbuffer_write_user(struct dvb_ringbuffer *rbuf,
 	}
 	status = copy_from_user(rbuf->data+rbuf->pwrite, buf, todo);
 	if (status)
-		return len - todo;
+		return -EFAULT;
 	/* smp_store_release() for write pointer update, see above */
 	smp_store_release(&rbuf->pwrite, (rbuf->pwrite + todo) % rbuf->size);
 
-- 
2.30.2