netdev-offload: Fix Clang's static analyzer 'Division by zero' warnings.

When enabling DPDK with the configure the below, ovs-vswitchd will crash. ovs-vsctl set Open_vSwitch . other_config:n-offload-threads=0 ovs-vsctl set Open_vSwitch . other_config:hw-offload=true This issue arises because setting the 'n-offload-threads' value to zero is not a supported configuration. This fix addresses this by implementing a check to ensure a valid 'n-offload-threads' value, both during configuration and statistics gathering. Fixes: 62c2d8a ("netdev-offload: Add multi-thread API.") Signed-off-by: Eelco Chaudron <[email protected]> Acked-by: Ilya Maximets <[email protected]> Signed-off-by: Simon Horman <[email protected]>
horms · Oct 30, 2023 · 1b0c753 · 1b0c753
1 parent 3919e61
commit 1b0c753
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Showing 4 changed files with 8 additions and 3 deletions.
diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
@@ -4748,6 +4748,10 @@ dpif_netdev_offload_stats_get(struct dpif *dpif,
     }
 
     nb_thread = netdev_offload_thread_nb();
+    if (!nb_thread) {
+        return EINVAL;
+    }
+
     /* nb_thread counters for the overall total as well. */
     stats->size = ARRAY_SIZE(hwol_stats) * (nb_thread + 1);
     stats->counters = xcalloc(stats->size, sizeof *stats->counters);

diff --git a/lib/netdev-offload.c b/lib/netdev-offload.c
@@ -872,7 +872,8 @@ netdev_set_flow_api_enabled(const struct smap *ovs_other_config)
             offload_thread_nb = smap_get_ullong(ovs_other_config,
                                                 "n-offload-threads",
                                                 DEFAULT_OFFLOAD_THREAD_NB);
-            if (offload_thread_nb > MAX_OFFLOAD_THREAD_NB) {
+            if (offload_thread_nb == 0 ||
+                offload_thread_nb > MAX_OFFLOAD_THREAD_NB) {
                 VLOG_WARN("netdev: Invalid number of threads requested: %u",
                           offload_thread_nb);
                 offload_thread_nb = DEFAULT_OFFLOAD_THREAD_NB;

diff --git a/tests/test-id-fpool.c b/tests/test-id-fpool.c
@@ -237,7 +237,7 @@ print_result(const char *prefix)
     for (i = 0; i < n_threads; i++) {
         avg += thread_working_ms[i];
     }
-    avg /= n_threads;
+    avg /= n_threads ? n_threads : 1;
     printf("%s: ", prefix);
     for (i = 0; i < n_threads; i++) {
         if (thread_working_ms[i] >= TIMEOUT_MS) {

diff --git a/tests/test-mpsc-queue.c b/tests/test-mpsc-queue.c
@@ -315,7 +315,7 @@ print_result(const char *prefix, int reader_elapsed)
     for (i = 0; i < n_threads; i++) {
         avg += thread_working_ms[i];
     }
-    avg /= n_threads;
+    avg /= n_threads ? n_threads : 1;
     printf("%s:  %6d", prefix, reader_elapsed);
     for (i = 0; i < n_threads; i++) {
         printf(" %6" PRIu64, thread_working_ms[i]);