add AFL_TRY_AFFINITY

3 files changed, 32 insertions, 10 deletions

diff --git a/src/afl-fuzz-init.c b/src/afl-fuzz-init.c
index f2d1fb9b..88b5bc02 100644
--- a/src/afl-fuzz-init.c
+++ b/src/afl-fuzz-init.c
@@ -113,7 +113,7 @@ void bind_to_free_cpu(afl_state_t *afl) {
   u8  lockfile[PATH_MAX] = "";
   s32 i;
 
-  if (afl->afl_env.afl_no_affinity) {
+  if (afl->afl_env.afl_no_affinity && !afl->afl_env.afl_try_affinity) {
 
     if (afl->cpu_to_bind != -1) {
 
@@ -130,10 +130,21 @@ void bind_to_free_cpu(afl_state_t *afl) {
 
     if (!bind_cpu(afl, afl->cpu_to_bind)) {
 
-      FATAL(
-          "Could not bind to requested CPU %d! Make sure you passed a valid "
-          "-b.",
-          afl->cpu_to_bind);
+      if (afl->afl_env.afl_try_affinity) {
+
+        WARNF(
+            "Could not bind to requested CPU %d! Make sure you passed a valid "
+            "-b.",
+            afl->cpu_to_bind);
+
+      } else {
+
+        FATAL(
+            "Could not bind to requested CPU %d! Make sure you passed a valid "
+            "-b.",
+            afl->cpu_to_bind);
+
+      }
 
     }
 
@@ -420,11 +431,14 @@ void bind_to_free_cpu(afl_state_t *afl) {
          "Uh-oh, looks like all %d CPU cores on your system are allocated to\n"
          "    other instances of afl-fuzz (or similar CPU-locked tasks). "
          "Starting\n"
-         "    another fuzzer on this machine is probably a bad plan, but if "
-         "you are\n"
-         "    absolutely sure, you can set AFL_NO_AFFINITY and try again.\n",
-         afl->cpu_core_count);
-    FATAL("No more free CPU cores");
+         "    another fuzzer on this machine is probably a bad plan.\n"
+         "%s",
+         afl->cpu_core_count,
+         afl->afl_env.afl_try_affinity ? ""
+                                       : "    If you are sure, you can set "
+                                         "AFL_NO_AFFINITY and try again.\n");
+
+    if (!afl->afl_env.afl_try_affinity) { FATAL("No more free CPU cores"); }
 
   }
 
diff --git a/src/afl-fuzz-state.c b/src/afl-fuzz-state.c
index 046d17d6..0658070e 100644
--- a/src/afl-fuzz-state.c
+++ b/src/afl-fuzz-state.c
@@ -202,6 +202,13 @@ void read_afl_environment(afl_state_t *afl, char **envp) {
             afl->afl_env.afl_no_affinity =
                 get_afl_env(afl_environment_variables[i]) ? 1 : 0;
 
+          } else if (!strncmp(env, "AFL_TRY_AFFINITY",
+
+                              afl_environment_variable_len)) {
+
+            afl->afl_env.afl_try_affinity =
+                get_afl_env(afl_environment_variables[i]) ? 1 : 0;
+
           } else if (!strncmp(env, "AFL_SKIP_CRASHES",
 
                               afl_environment_variable_len)) {
diff --git a/src/afl-fuzz.c b/src/afl-fuzz.c
index 3b6ac5e2..bb970e5f 100644
--- a/src/afl-fuzz.c
+++ b/src/afl-fuzz.c
@@ -220,6 +220,7 @@ static void usage(u8 *argv0, int more_help) {
       "                    then they are randomly selected instead all of them being\n"
       "                    used. Defaults to 200.\n"
       "AFL_NO_AFFINITY: do not check for an unused cpu core to use for fuzzing\n"
+      "AFL_TRY_AFFINITY: try to bind to an unused core, but don't fail if unsuccessful\n"
       "AFL_NO_ARITH: skip arithmetic mutations in deterministic stage\n"
       "AFL_NO_AUTODICT: do not load an offered auto dictionary compiled into a target\n"
       "AFL_NO_CPU_RED: avoid red color for showing very high cpu usage\n"