Change how the mailer is waited for. Instead of having a SIGCHLD

handler, use the double fork trick to orphan the child that opens
the pipe to sendmail.  Fixes a problem running su on some Linux distros.

logging.c

@@ -425,8 +425,8 @@ send_mail(line)
 {
     FILE *mail;
     char *p;
-    int pfd[2];
-    pid_t pid;
+    int pfd[2], status;
+    pid_t pid, rv;
     sigaction_t sa, saved_sa_pipe;
 #ifndef NO_ROOT_MAILER
     static char *root_envp[] = {
@@ -443,19 +443,58 @@ send_mail(line)
     if (!def_mailerpath || !def_mailto)
 	return;
 
+    /* Fork a child so we can be asyncronous. */
+    switch (pid = fork()) {
+	case -1:
+	    /* Error. */
+	    error(1, "cannot fork");
+	    break;
+	case 0:
+	    /* Child continues below. */
+	    break;
+	default:
+	    /* Parent waits and returns. */
+	    do {
+#ifdef sudo_waitpid
+		rv = sudo_waitpid(pid, &status, 0);
+#else
+		rv = wait(&status);
+#endif
+	    } while (rv == -1 && errno == EINTR);
+	    return;
+    }
+
+    /* Fork again and orphan the grandchild so parent can continue. */
+    switch (pid = fork()) {
+	case -1:
+	    /* Error. */
+	    warning("cannot fork");
+	    _exit(1);
+	    break;
+	case 0:
+	    /* Grandchild continues below. */
+	    break;
+	default:
+	    /* Orphan grandchild. */
+	    _exit(0);
+    }
+
     /* Ignore SIGPIPE in case mailer exits prematurely (or is missing). */
     sigemptyset(&sa.sa_mask);
     sa.sa_flags = 0;
     sa.sa_handler = SIG_IGN;
     (void) sigaction(SIGPIPE, &sa, &saved_sa_pipe);
 
-    if (pipe(pfd) == -1)
-	error(1, "cannot open pipe");
+    if (pipe(pfd) == -1) {
+	warning("cannot open pipe");
+	_exit(1);
+    }
 
     switch (pid = fork()) {
 	case -1:
 	    /* Error. */
-	    error(1, "cannot fork");
+	    warning("cannot fork");
+	    _exit(1);
 	    break;
 	case 0:
 	    {
@@ -463,7 +502,7 @@ send_mail(line)
 		char *mpath, *mflags;
 		int i;
 
-		/* Child, set stdin to output side of the pipe */
+		/* Great-grandchild, set stdin to output side of the pipe */
 		if (pfd[0] != STDIN_FILENO) {
 		    (void) dup2(pfd[0], STDIN_FILENO);
 		    (void) close(pfd[0]);
@@ -533,7 +572,13 @@ send_mail(line)
     (void) fprintf(mail, "\n\n%s : %s : %s : %s\n\n", user_host,
 	get_timestr(), user_name, line);
     fclose(mail);
-
+    do {
+#ifdef sudo_waitpid
+        rv = sudo_waitpid(pid, &status, 0);
+#else
+        rv = wait(&status);
+#endif
+    } while (rv == -1 && errno == EINTR);
     (void) sigaction(SIGPIPE, &saved_sa_pipe, NULL);
 }
 
@@ -551,26 +596,6 @@ should_mail(status)
 	(def_mail_no_perms && !ISSET(status, VALIDATE_OK)));
 }
 
-/*
- * SIGCHLD sig handler--wait for children as they die.
- */
-RETSIGTYPE
-reapchild(sig)
-    int sig;
-{
-    int status, serrno = errno;
-#ifdef sudo_waitpid
-    pid_t pid;
-
-    do {
-	pid = sudo_waitpid(-1, &status, WNOHANG);
-    } while (pid != 0 && (pid != -1 || errno == EINTR));
-#else
-    (void) wait(&status);
-#endif
-    errno = serrno;
-}
-
 /*
  * Return an ascii string with the current date + time
  * Uses strftime() if available, else falls back to ctime().

sudo.c

@@ -153,7 +153,7 @@ login_cap_t *lc;
 #ifdef HAVE_BSD_AUTH_H
 char *login_style;
 #endif /* HAVE_BSD_AUTH_H */
-sigaction_t saved_sa_int, saved_sa_quit, saved_sa_tstp, saved_sa_chld;
+sigaction_t saved_sa_int, saved_sa_quit, saved_sa_tstp;
 static char *runas_user;
 static char *runas_group;
 static struct sudo_nss_list *snl;
@@ -208,8 +208,6 @@ main(argc, argv, envp)
     (void) sigaction(SIGINT, &sa, &saved_sa_int);
     (void) sigaction(SIGQUIT, &sa, &saved_sa_quit);
     (void) sigaction(SIGTSTP, &sa, &saved_sa_tstp);
-    sa.sa_handler = reapchild;
-    (void) sigaction(SIGCHLD, &sa, &saved_sa_chld);
 
     /*
      * Turn off core dumps and make sure fds 0-2 are open.
@@ -492,7 +490,6 @@ main(argc, argv, envp)
 	(void) sigaction(SIGINT, &saved_sa_int, NULL);
 	(void) sigaction(SIGQUIT, &saved_sa_quit, NULL);
 	(void) sigaction(SIGTSTP, &saved_sa_tstp, NULL);
-	(void) sigaction(SIGCHLD, &saved_sa_chld, NULL);
 
 	/* Close the password and group files and free up memory. */
 	sudo_endpwent();

sudo_edit.c

@@ -59,7 +59,7 @@
 __unused static const char rcsid[] = "$Sudo$";
 #endif /* lint */
 
-extern sigaction_t saved_sa_int, saved_sa_quit, saved_sa_tstp, saved_sa_chld;
+extern sigaction_t saved_sa_int, saved_sa_quit, saved_sa_tstp;
 extern char **environ;
 
 /*
@@ -226,11 +226,10 @@ int sudo_edit(argc, argv, envp)
 	nargv[ac++] = tf[i++].tfile;
     nargv[ac] = NULL;
 
-    /* We wait for our own children and can be suspended. */
+    /* Allow the editor to be suspended. */
     sigemptyset(&sa.sa_mask);
     sa.sa_flags = SA_RESTART;
     sa.sa_handler = SIG_DFL;
-    (void) sigaction(SIGCHLD, &sa, NULL);
     (void) sigaction(SIGTSTP, &saved_sa_tstp, NULL);
 
     /*
@@ -246,7 +245,6 @@ int sudo_edit(argc, argv, envp)
 	/* child */
 	(void) sigaction(SIGINT, &saved_sa_int, NULL);
 	(void) sigaction(SIGQUIT, &saved_sa_quit, NULL);
-	(void) sigaction(SIGCHLD, &saved_sa_chld, NULL);
 	set_perms(PERM_FULL_USER);
 	closefrom(def_closefrom + 1);
 	execvp(nargv[0], nargv);

visudo.c

@@ -651,19 +651,13 @@ run_command(path, argv)
     char **argv;
 {
     int status;
-    pid_t pid;
-    sigset_t set, oset;
-
-    (void) sigemptyset(&set);
-    (void) sigaddset(&set, SIGCHLD);
-    (void) sigprocmask(SIG_BLOCK, &set, &oset);
+    pid_t pid, rv;
 
     switch (pid = fork()) {
 	case -1:
 	    error(1, "unable to run %s", path);
 	    break;	/* NOTREACHED */
 	case 0:
-	    (void) sigprocmask(SIG_SETMASK, &oset, NULL);
 	    sudo_endpwent();
 	    sudo_endgrent();
 	    closefrom(STDERR_FILENO + 1);
@@ -673,15 +667,15 @@ run_command(path, argv)
 	    break;	/* NOTREACHED */
     }
 
+    do {
 #ifdef sudo_waitpid
-    pid = sudo_waitpid(pid, &status, 0);
+	rv = sudo_waitpid(pid, &status, 0);
 #else
-    pid = wait(&status);
+	rv = wait(&status);
 #endif
+    } while (rv == -1 && errno == EINTR);
 
-    (void) sigprocmask(SIG_SETMASK, &oset, NULL);
-
-    if (pid == -1 || !WIFEXITED(status))
+    if (rv == -1 || !WIFEXITED(status))
 	return(-1);
     return(WEXITSTATUS(status));
 }