[PATCH v3 15/16] vhost: check for overflow in xstat name

[Stephen Hemminger <stephen@networkplumber.org>]

The snprintf to format an xstat name could overflow if called with
a long rte_vhost_stat_name. Check if that happens and warn.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 lib/vhost/vhost.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/lib/vhost/vhost.c b/lib/vhost/vhost.c
index 416f082dca..540f4e0635 100644
--- a/lib/vhost/vhost.c
+++ b/lib/vhost/vhost.c
@@ -2200,6 +2200,7 @@ rte_vhost_vring_stats_get_names(int vid, uint16_t queue_id,
 {
 	struct virtio_net *dev = get_device(vid);
 	unsigned int i;
+	int ret;
 
 	if (dev == NULL)
 		return -1;
@@ -2213,10 +2214,15 @@ rte_vhost_vring_stats_get_names(int vid, uint16_t queue_id,
 	if (name == NULL || size < VHOST_NB_VQ_STATS)
 		return VHOST_NB_VQ_STATS;
 
-	for (i = 0; i < VHOST_NB_VQ_STATS; i++)
-		snprintf(name[i].name, sizeof(name[i].name), "%s_q%u_%s",
-				(queue_id & 1) ? "rx" : "tx",
-				queue_id / 2, vhost_vq_stat_strings[i].name);
+	for (i = 0; i < VHOST_NB_VQ_STATS; i++) {
+		ret = snprintf(name[i].name, sizeof(name[i].name), "%s_q%u_%s",
+			       (queue_id & 1) ? "rx" : "tx",
+			       queue_id / 2, vhost_vq_stat_strings[i].name);
+		if (ret >= (int)sizeof(name[0].name))
+			VHOST_CONFIG_LOG("device", NOTICE, "truncated xstat '%s_q%u_%s'",
+					 (queue_id & 1) ? "rx" : "tx",
+					 queue_id / 2, vhost_vq_stat_strings[i].name);
+	}
 
 	return VHOST_NB_VQ_STATS;
 }
-- 
2.51.0