[PATCH 7/9] vhost: add WARNING if log_num is more than limit

[Dongli Zhang]

Since long time ago, the only user of vq->log is vhost-net. The concern is
to add support for more devices (i.e. vhost-scsi or vsock) may reveals
unknown issue in the vhost API. Add a WARNING.

Suggested-by: Joao Martins <joao.m.mart...@oracle.com>
Signed-off-by: Dongli Zhang <dongli.zh...@oracle.com>
---
 drivers/vhost/vhost.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index db3b30aba940..8368370b40f7 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -2553,6 +2553,15 @@ static int get_indirect(struct vhost_virtqueue *vq,
                if (access == VHOST_ACCESS_WO) {
                        *in_num += ret;
                        if (unlikely(log && ret)) {
+                               /*
+                                * Since long time ago, the only user of
+                                * vq->log is vhost-net. The concern is to
+                                * add support for more devices (i.e.
+                                * vhost-scsi or vsock) may reveals unknown
+                                * issue in the vhost API. Add a WARNING.
+                                */
+                               WARN_ON_ONCE(*log_num >= vq->dev->iov_limit);
+
                                log[*log_num].addr = vhost64_to_cpu(vq, 
desc.addr);
                                log[*log_num].len = vhost32_to_cpu(vq, 
desc.len);
                                ++*log_num;
@@ -2673,6 +2682,15 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq,
                         * increment that count. */
                        *in_num += ret;
                        if (unlikely(log && ret)) {
+                               /*
+                                * Since long time ago, the only user of
+                                * vq->log is vhost-net. The concern is to
+                                * add support for more devices (i.e.
+                                * vhost-scsi or vsock) may reveals unknown
+                                * issue in the vhost API. Add a WARNING.
+                                */
+                               WARN_ON_ONCE(*log_num >= vq->dev->iov_limit);
+
                                log[*log_num].addr = vhost64_to_cpu(vq, 
desc.addr);
                                log[*log_num].len = vhost32_to_cpu(vq, 
desc.len);
                                ++*log_num;
-- 
2.39.3