[PATCH net-next V2 1/3] vhost: fail early when __vhost_add_used() fails

[Jason Wang]

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 <epere...@redhat.com>
Signed-off-by: Jason Wang <jasow...@redhat.com>
---
 drivers/vhost/vhost.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 3a5ebb973dba..d1d3912f4804 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -2775,6 +2775,9 @@ 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)) {
-- 
2.39.5