From: Jason Wang <jasowang@redhat.com>
Date: Mon, 14 Jul 2025 08:47:53 +0000 (+0800)
Subject: vhost: fail early when __vhost_add_used() fails
X-Git-Tag: v6.12.43~173
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=a1a63d8a442d09ccc38af1618391f626c4fa0c49;p=thirdparty%2Fkernel%2Fstable.git

vhost: fail early when __vhost_add_used() fails

[ Upstream commit b4ba1207d45adaafa2982c035898b36af2d3e518 ]

This patch fails vhost_add_used_n() early when __vhost_add_used()
fails to make sure used idx is not updated with stale used ring
information.

Reported-by: Eugenio Pérez <eperezma@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20250714084755.11921-2-jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 79b0b7cd28601..71604668e53f6 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -2971,6 +2971,9 @@ int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
 	}
 	r = __vhost_add_used_n(vq, heads, count);
 
+	if (r < 0)
+		return r;
+
 	/* Make sure buffer is written before we update index. */
 	smp_wmb();
 	if (vhost_put_used_idx(vq)) {