From: Klement Sekera <ksekera@cisco.com>
Date: Wed, 24 Jun 2020 13:13:46 +0000 (+0000)
Subject: nat: avoid division by zero
X-Git-Tag: v21.01-rc0~249
X-Git-Url: https://gerrit.fd.io/r/gitweb?a=commitdiff_plain;h=fe77bdc1906cca6a76bd44b1aceffc971f64cec4;p=vpp.git

nat: avoid division by zero

Return error instead of dividing by zero.

Type: fix
Signed-off-by: Klement Sekera <ksekera@cisco.com>
Change-Id: I9f6a942e87ab87e8f1921e744ec1add45884e74a
---

diff --git a/src/plugins/nat/nat_det.c b/src/plugins/nat/nat_det.c
index cad0d2ae5af..65a669bceb9 100644
--- a/src/plugins/nat/nat_det.c
+++ b/src/plugins/nat/nat_det.c
@@ -82,13 +82,20 @@ snat_det_add_map (snat_main_t * sm, ip4_address_t * in_addr, u8 in_plen,
 	  num_sessions = num_sessions * 1000 - 1;
 	}
 
+      u32 sharing_ratio = (1 << (32 - in_plen)) / (1 << (32 - out_plen));
+      if (!sharing_ratio)
+	{
+	  // avoid division by zero
+	  return VNET_API_ERROR_INVALID_VALUE;
+	}
+
       pool_get (sm->det_maps, det_map);
       clib_memset (det_map, 0, sizeof (*det_map));
       det_map->in_addr.as_u32 = in_cmp.as_u32;
       det_map->in_plen = in_plen;
       det_map->out_addr.as_u32 = out_cmp.as_u32;
       det_map->out_plen = out_plen;
-      det_map->sharing_ratio = (1 << (32 - in_plen)) / (1 << (32 - out_plen));
+      det_map->sharing_ratio = sharing_ratio;
       det_map->ports_per_host = (65535 - 1023) / det_map->sharing_ratio;
 
       vec_validate_init_empty (det_map->sessions, num_sessions,