flow/manager: fix coverity divide_by_zero warning

Updated all cases where flow_config.prealloc was used in a division.

*** CID 1524506:  Integer handling issues  (DIVIDE_BY_ZERO)
/src/flow-manager.c: 858 in FlowManager()
852                                "flow_spare_q status: %" PRIu32 "%% flows at the queue",
853                             spare_pool_len, flow_config.prealloc,
854                             spare_pool_len * 100 / flow_config.prealloc);
855
856                     /* only if we have pruned this "emergency_recovery" percentage
857                      * of flows, we will unset the emergency bit */
>>>     CID 1524506:  Integer handling issues  (DIVIDE_BY_ZERO)
>>>     In expression "spare_pool_len * 100U / flow_config.prealloc", division by expression "flow_config.prealloc" which may be zero has undefined behavior.
858                     if (spare_pool_len * 100 / flow_config.prealloc > flow_config.emergency_recovery) {
859                         emerg_over_cnt++;
860                     } else {
861                         emerg_over_cnt = 0;
862                     }

Related to
Bug #5919

(cherry picked from commit 754d2803dd5f5956b7f2ae947f933ef03cf1d15b)

diff --git a/src/flow-manager.c b/src/flow-manager.c
index e9b37c294803900e4d5619a1caf0a3ebc6ae42b0..2b2b2b4a7a7984380e73e0902171b9afc68977ac 100644 (file)
--- a/src/flow-manager.c
+++ b/src/flow-manager.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 2007-2020 Open Information Security Foundation
+/* Copyright (C) 2007-2023 Open Information Security Foundation
  *
  * You can copy, redistribute or modify this Program under the terms of
  * the GNU General Public License version 2 as published by the Free
@@ -901,11 +901,11 @@ static TmEcode FlowManager(ThreadVars *th_v, void *thread_data)
             if (emerg == true) {
                 SCLogDebug("flow_sparse_q.len = %"PRIu32" prealloc: %"PRIu32
                         "flow_spare_q status: %"PRIu32"%% flows at the queue",
-                        len, flow_config.prealloc, len * 100 / flow_config.prealloc);
+                        len, flow_config.prealloc, len * 100 / MAX(flow_config.prealloc, 1));
 
             /* only if we have pruned this "emergency_recovery" percentage
              * of flows, we will unset the emergency bit */
-            if (len * 100 / flow_config.prealloc > flow_config.emergency_recovery) {
+            if (len * 100 / MAX(flow_config.prealloc, 1) > flow_config.emergency_recovery) {
                 emerg_over_cnt++;
             } else {
                 emerg_over_cnt = 0;
@@ -923,7 +923,7 @@ static TmEcode FlowManager(ThreadVars *th_v, void *thread_data)
                           " FLOW_EMERGENCY bit (ts.tv_sec: %"PRIuMAX", "
                           "ts.tv_usec:%"PRIuMAX") flow_spare_q status(): %"PRIu32
                           "%% flows at the queue", (uintmax_t)ts.tv_sec,
-                          (uintmax_t)ts.tv_usec, len * 100 / flow_config.prealloc);
+                          (uintmax_t)ts.tv_usec, len * 100 / MAX(flow_config.prealloc, 1));
 
                 StatsIncr(th_v, ftd->cnt.flow_emerg_mode_over);
             }