From: Steve Chew (stechew) <stechew@cisco.com>
Date: Sun, 15 Sep 2019 16:04:45 +0000 (-0400)
Subject: Merge pull request #1743 in SNORT/snort3 from ~STECHEW/snort3:prune_unis_fix to master
X-Git-Tag: 3.0.0-262~37
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2ccf5e753565e792c9c63dd25ab3c0b467f90840;p=thirdparty%2Fsnort3.git

Merge pull request #1743 in SNORT/snort3 from ~STECHEW/snort3:prune_unis_fix to master

Squashed commit of the following:

commit 544acc5afc312a7aea9c35d726171e52c2edc2d2
Author: Steve Chew <stechew@cisco.com>
Date:   Thu Sep 12 21:50:36 2019 -0400

    flow: When walking uni_list stop before reaching head.
---

diff --git a/src/flow/flow_cache.cc b/src/flow/flow_cache.cc
index 817a2f87d..28f332fa4 100644
--- a/src/flow/flow_cache.cc
+++ b/src/flow/flow_cache.cc
@@ -236,7 +236,7 @@ unsigned FlowCache::prune_unis(PktType pkt_type)
     while ( (uni_list->get_count() > max_uni) && flow && (pruned < cleanup_flows) )
     {
         Flow* prune_me = flow;
-        flow = prune_me->prev;
+        flow = uni_list->get_prev(prune_me);
 
         if ( prune_me->was_blocked() )
             continue;
diff --git a/src/flow/flow_uni_list.h b/src/flow/flow_uni_list.h
index 7c138e086..fd04f747d 100644
--- a/src/flow/flow_uni_list.h
+++ b/src/flow/flow_uni_list.h
@@ -31,9 +31,10 @@ public:
     {
         head = new snort::Flow;
         tail = new snort::Flow;
-
         head->next = tail;
         tail->prev = head;
+        head->prev = nullptr;
+        tail->next = nullptr;
     }
 
     ~FlowUniList()
@@ -44,13 +45,10 @@ public:
 
     void link_uni(snort::Flow* flow)
     {
-
         flow->next = head->next;
         flow->prev = head;
-
         head->next->prev = flow;
         head->next = flow;
-
         ++count;
     }
 
@@ -59,16 +57,22 @@ public:
         if ( !flow->next )
             return;
 
-        --count;
-
         flow->next->prev = flow->prev;
         flow->prev->next = flow->next;
-
         flow->next = flow->prev = nullptr;
+        --count;
+
     }
 
     snort::Flow* get_oldest_uni()
-    { return tail->prev; }
+    {
+        return ( tail->prev != head ) ? tail->prev : nullptr;
+    }
+
+    snort::Flow* get_prev(snort::Flow* flow)
+    {
+        return ( flow->prev != head ) ? flow->prev : nullptr;
+    }
 
     unsigned get_count() const
     { return count; }