linux-kernel - [PATCH] vhost: vringh: Fix copy_to

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Message-ID: <cd637504a6e3967954a9e80fc1b75e8c0978087b.1758664002.git.mst@redhat.com>
Date: Tue, 23 Sep 2025 17:47:53 -0400
From: "Michael S. Tsirkin" <mst@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: zhang jiao <zhangjiao2@...s.chinamobile.com>,
	Jason Wang <jasowang@...hat.com>,
	Eugenio Pérez <eperezma@...hat.com>,
	kvm@...r.kernel.org, virtualization@...ts.linux.dev,
	netdev@...r.kernel.org
Subject: [PATCH] vhost: vringh: Fix copy_to_iter return value check

The return value of copy_to_iter can't be negative, check whether the
copied length is equal to the requested length instead of checking for
negative values.

Cc: zhang jiao <zhangjiao2@...s.chinamobile.com>
Link: https://lore.kernel.org/all/20250910091739.2999-1-zhangjiao2@cmss.chinamobile.com
Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
---


Lightly tested. zhang jiao could you pls also test, either ack or
fold into your patch?

 drivers/vhost/vringh.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c
index 0c8a17cbb22e..925858cc6096 100644
--- a/drivers/vhost/vringh.c
+++ b/drivers/vhost/vringh.c
@@ -1162,6 +1162,7 @@ static inline int copy_to_iotlb(const struct vringh *vrh, void *dst,
 		struct iov_iter iter;
 		u64 translated;
 		int ret;
+		size_t size;
 
 		ret = iotlb_translate(vrh, (u64)(uintptr_t)dst,
 				      len - total_translated, &translated,
@@ -1179,9 +1180,9 @@ static inline int copy_to_iotlb(const struct vringh *vrh, void *dst,
 				      translated);
 		}
 
-		ret = copy_to_iter(src, translated, &iter);
-		if (ret < 0)
-			return ret;
+		size = copy_to_iter(src, translated, &iter);
+		if (size != translated)
+			return -EFAULT;
 
 		src += translated;
 		dst += translated;
-- 
MST