Create a shallow copy of environ before replacing it in setproctitle()

Because clearenv() or setenv() might free the environ array of pointers,
we should make sure to copy it so that we can access it later on when
doing the deep copy via setenv().

Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=65470

diff --git a/src/setproctitle.c b/src/setproctitle.c
index 0d979543b242e2f9da8ac9b9f29a2368bd35e7af..7e4b16567e96bfce4bbbb29d5b90c135b7eac6df 100644 (file)
--- a/src/setproctitle.c
+++ b/src/setproctitle.c
@@ -76,36 +76,60 @@ spt_clearenv(void)
 }
 
 static int
-spt_copyenv(char *oldenv[])
+spt_copyenv(int envc, char *envp[])
 {
+       char **envcopy;
        char *eq;
+       int envsize;
        int i, error;
 
-       if (environ != oldenv)
+       if (environ != envp)
                return 0;
 
+       /* Make a copy of the old environ array of pointers, in case
+        * clearenv() or setenv() is implemented to free the internal
+        * environ array, because we will need to access the old environ
+        * contents to make the new copy. */
+       envsize = (envc + 1) * sizeof(char *);
+       envcopy = malloc(envsize);
+       if (envcopy == NULL)
+               return errno;
+       memcpy(envcopy, envp, envsize);
+
        error = spt_clearenv();
        if (error) {
-               environ = oldenv;
+               environ = envp;
+               free(envcopy);
                return error;
        }
 
-       for (i = 0; oldenv[i]; i++) {
-               eq = strchr(oldenv[i], '=');
+       for (i = 0; envcopy[i]; i++) {
+               eq = strchr(envcopy[i], '=');
                if (eq == NULL)
                        continue;
 
                *eq = '\0';
-               if (setenv(oldenv[i], eq + 1, 1) < 0)
+               if (setenv(envcopy[i], eq + 1, 1) < 0)
                        error = errno;
                *eq = '=';
 
                if (error) {
-                       environ = oldenv;
+#ifdef HAVE_CLEARENV
+                       /* Because the old environ might not be available
+                        * anymore we will make do with the shallow copy. */
+                       environ = envcopy;
+#else
+                       environ = envp;
+                       free(envcopy);
+#endif
                        return error;
                }
        }
 
+       /* Dispose of the shallow copy, now that we've finished transfering
+        * the old environment. */
+       free(envcopy);
+
        return 0;
 }
 
@@ -133,7 +157,7 @@ static void
 spt_init(int argc, char *argv[], char *envp[])
 {
        char *base, *end, *nul, *tmp;
-       int i, error;
+       int i, envc, error;
 
        /* Try to make sure we got called with main() arguments. */
        if (argc < 0)
@@ -159,6 +183,7 @@ spt_init(int argc, char *argv[], char *envp[])
 
                end = envp[i] + strlen(envp[i]) + 1;
        }
+       envc = i;
 
        SPT.arg0 = strdup(argv[0]);
        if (SPT.arg0 == NULL) {
@@ -173,7 +198,7 @@ spt_init(int argc, char *argv[], char *envp[])
        }
        setprogname(tmp);
 
-       error = spt_copyenv(envp);
+       error = spt_copyenv(envc, envp);
        if (error) {
                SPT.error = error;
                return;