From: Vincent Bernat <vincent@bernat.im>
Date: Sun, 13 Mar 2016 11:04:06 +0000 (+0100)
Subject: interfaces: limit the maximum search depth when applying a VLAN
X-Git-Tag: 0.9.2~39
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=e7e6676e05879c364d6d79288f06d4098d2b2775;p=thirdparty%2Flldpd.git

interfaces: limit the maximum search depth when applying a VLAN

It's now quite easy to hit a bug where we loop over interfaces when
trying to find the physical interface associated to a VLAN. Put a
maximum depth of 5.
---

diff --git a/NEWS b/NEWS
index 058a07e6..3022f7e3 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,7 @@ lldpd (0.9.2)
   * Change:
     + Ability to add/remove/replace custom TLV from lldpcli.
     + LLDP-MED capabilities are displayed differently in lldpcli.
+    + Limit the maximum depth (5) when trying to apply a VLAN.
   * Fix:
     + LLDP-MED POE TLV are now displayed in lldpcli.
     + Ignore lower link when it is in another namespace.
diff --git a/src/daemon/interfaces.c b/src/daemon/interfaces.c
index b3f99346..8c18be09 100644
--- a/src/daemon/interfaces.c
+++ b/src/daemon/interfaces.c
@@ -223,6 +223,7 @@ iface_append_vlan(struct lldpd *cfg,
  *
  * @param vlan  The VLAN interface (used to get VLAN ID).
  * @param upper The upper interface we are currently examining.
+ * @param depth Depth of the stack (avoid infinite recursion)
  *
  * Initially, upper == vlan. This function will be called recursively.
  */
@@ -230,8 +231,16 @@ static void
 iface_append_vlan_to_lower(struct lldpd *cfg,
     struct interfaces_device_list *interfaces,
     struct interfaces_device *vlan,
-    struct interfaces_device *upper)
+    struct interfaces_device *upper,
+    int depth)
 {
+	if (depth > 5) {
+		log_debug("interfaces",
+		    "maximum depth reached when applying VLAN %s (loop?)",
+		    vlan->name);
+		return;
+	}
+	depth++;
 	struct interfaces_device *lower;
 	log_debug("interfaces",
 	    "looking to apply VLAN %s to physical interface behind %s",
@@ -243,7 +252,8 @@ iface_append_vlan_to_lower(struct lldpd *cfg,
 		    vlan->name, upper->name);
 		iface_append_vlan_to_lower(cfg,
 		    interfaces, vlan,
-		    upper->lower);
+		    upper->lower,
+		    depth);
 		return;
 	}
 
@@ -262,7 +272,7 @@ iface_append_vlan_to_lower(struct lldpd *cfg,
 		log_debug("interfaces", "VLAN %s on lower interface %s",
 		    vlan->name, upper->name);
 		iface_append_vlan_to_lower(cfg,
-		    interfaces, vlan, lower);
+		    interfaces, vlan, lower, depth);
 	}
 }
 
@@ -283,7 +293,7 @@ interfaces_helper_vlan(struct lldpd *cfg,
 		log_debug("interfaces", "search physical interface for VLAN interface %s",
 		    iface->name);
 		iface_append_vlan_to_lower(cfg, interfaces,
-		    iface, iface);
+		    iface, iface, 0);
 	}
 }
 #endif