suggested env vars for lazy ppl

include/common.h

@@ -39,6 +39,7 @@
 #define STRINGIFY_VAL_SIZE_MAX (16)
 
 void detect_file_args(char **argv, u8 *prog_in, bool *use_stdin);
+void print_suggested_envs(char *mispelled_env);
 void check_environment_vars(char **env);
 
 char **argv_cpy_dup(int argc, char **argv);

qemu_mode/libqasan/dlmalloc.c

@@ -3917,6 +3917,7 @@ static void internal_malloc_stats(mstate m) {
                                                                 \
         } else if (RTCHECK(B == smallbin_at(M, I) ||            \
                                                                 \
+                                                                \
                            (ok_address(M, B) && B->fd == P))) { \
                                                                 \
           F->bk = B;                                            \
@@ -4128,6 +4129,7 @@ static void internal_malloc_stats(mstate m) {
                                                                      \
         } else                                                       \
                                                                      \
+                                                                     \
           CORRUPTION_ERROR_ACTION(M);                                \
         if (R != 0) {                                                \
                                                                      \
@@ -4144,6 +4146,7 @@ static void internal_malloc_stats(mstate m) {
                                                                      \
               } else                                                 \
                                                                      \
+                                                                     \
                 CORRUPTION_ERROR_ACTION(M);                          \
                                                                      \
             }                                                        \
@@ -4156,12 +4159,14 @@ static void internal_malloc_stats(mstate m) {
                                                                      \
               } else                                                 \
                                                                      \
+                                                                     \
                 CORRUPTION_ERROR_ACTION(M);                          \
                                                                      \
             }                                                        \
                                                                      \
           } else                                                     \
                                                                      \
+                                                                     \
             CORRUPTION_ERROR_ACTION(M);                              \
                                                                      \
         }                                                            \

src/afl-common.c

@@ -518,6 +518,120 @@ int parse_afl_kill_signal_env(u8 *afl_kill_signal_env, int default_signal) {
 
 }
 
+#define HELPER_MIN3(a, b, c) \
+  ((a) < (b) ? ((a) < (c) ? (a) : (c)) : ((b) < (c) ? (b) : (c)))
+
+// from
+// https://en.wikibooks.org/wiki/Algorithm_Implementation/Strings/Levenshtein_distance#C
+static int string_distance_levenshtein(char *s1, char *s2) {
+
+  unsigned int s1len, s2len, x, y, lastdiag, olddiag;
+  s1len = strlen(s1);
+  s2len = strlen(s2);
+  unsigned int column[s1len + 1];
+  for (y = 1; y <= s1len; y++)
+    column[y] = y;
+  for (x = 1; x <= s2len; x++) {
+
+    column[0] = x;
+    for (y = 1, lastdiag = x - 1; y <= s1len; y++) {
+
+      olddiag = column[y];
+      column[y] = HELPER_MIN3(column[y] + 1, column[y - 1] + 1,
+                              lastdiag + (s1[y - 1] == s2[x - 1] ? 0 : 1));
+      lastdiag = olddiag;
+
+    }
+
+  }
+
+  return column[s1len];
+
+}
+
+#undef HELPER_MIN3
+
+void print_suggested_envs(char *mispelled_env) {
+
+  size_t env_name_len =
+      strcspn(mispelled_env, "=") - 4;  // remove the AFL_prefix
+  char *env_name = ck_alloc(env_name_len + 1);
+  memcpy(env_name, mispelled_env + 4, env_name_len);
+
+  char *seen = ck_alloc(sizeof(afl_environment_variables) / sizeof(char *));
+
+  int j;
+  for (j = 0; afl_environment_variables[j] != NULL; ++j) {
+
+    char *afl_env = afl_environment_variables[j] + 4;
+
+    int distance = string_distance_levenshtein(afl_env, env_name);
+    if (distance <= 3 && seen[j] == 0) {
+
+      SAYF("Did you mean %s?\n", afl_environment_variables[j]);
+      seen[j] = 1;
+
+    }
+
+    size_t afl_env_len = strlen(afl_env);
+    char * reduced = ck_alloc(afl_env_len + 1);
+
+    size_t start = 0;
+    while (start < afl_env_len) {
+
+      size_t end = start + strcspn(afl_env + start, "_") + 1;
+      memcpy(reduced, afl_env, start);
+      if (end < afl_env_len)
+        memcpy(reduced + start, afl_env + end, afl_env_len - end);
+      reduced[afl_env_len - end + start] = 0;
+
+      int distance = string_distance_levenshtein(reduced, env_name);
+      if (distance <= 3 && seen[j] == 0) {
+
+        SAYF("Did you mean %s?\n", afl_environment_variables[j]);
+        seen[j] = 1;
+
+      }
+
+      start = end;
+
+    };
+
+  }
+
+  char * reduced = ck_alloc(env_name_len + 1);
+  size_t start = 0;
+  while (start < env_name_len) {
+
+    size_t end = start + strcspn(env_name + start, "_") + 1;
+    memcpy(reduced, env_name, start);
+    if (end < env_name_len)
+      memcpy(reduced + start, env_name + end, env_name_len - end);
+    reduced[env_name_len - end + start] = 0;
+
+    for (j = 0; afl_environment_variables[j] != NULL; ++j) {
+
+      int distance = string_distance_levenshtein(
+          afl_environment_variables[j] + 4, reduced);
+      if (distance <= 3 && seen[j] == 0) {
+
+        SAYF("Did you mean %s?\n", afl_environment_variables[j]);
+        seen[j] = 1;
+
+      }
+
+    }
+
+    start = end;
+
+  };
+
+  ck_free(env_name);
+  ck_free(reduced);
+  ck_free(seen);
+
+}
+
 void check_environment_vars(char **envp) {
 
   if (be_quiet) { return; }
@@ -587,6 +701,8 @@ void check_environment_vars(char **envp) {
         WARNF("Mistyped AFL environment variable: %s", env);
         issue_detected = 1;
 
+        print_suggested_envs(env);
+
       }
 
     }

src/afl-fuzz-state.c

@@ -486,6 +486,8 @@ void read_afl_environment(afl_state_t *afl, char **envp) {
         WARNF("Mistyped AFL environment variable: %s", env);
         issue_detected = 1;
 
+        print_suggested_envs(env);
+
       }
 
     }