[dpdk-dev] [PATCH 5/8] vhost: reject invalid log base mmap_offset values

[Stefan Hajnoczi]

If the log base mmap_offset is larger than mmap_size then it points
outside the mmap region.  We must not write to memory outside the mmap
region, so validate mmap_offset in vhost_user_set_log_base().

Signed-off-by: Stefan Hajnoczi <stefanha at redhat.com>
---
 lib/librte_vhost/vhost_user.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
index 48b493d70..fd47404ce 100644
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -1005,6 +1005,15 @@ vhost_user_set_log_base(struct virtio_net *dev, struct VhostUserMsg *msg)
 
 	size = msg->payload.log.mmap_size;
 	off  = msg->payload.log.mmap_offset;
+
+	/* Don't allow mmap_offset to point outside the mmap region */
+	if (off > size) {
+		RTE_LOG(ERR, VHOST_CONFIG,
+			"log offset %#"PRIx64" exceeds log size %#"PRIx64"\n",
+			off, size);
+		return -1;
+	}
+
 	RTE_LOG(INFO, VHOST_CONFIG,
 		"log mmap size: %"PRId64", offset: %"PRId64"\n",
 		size, off);
-- 
2.14.3