From: Christian Kastner <ckk@kvr.at>
Date: Sun, 20 Dec 2015 14:04:46 +0100
Subject: Memory allocation issues

Check the results of malloc(), strdup(), etc., and don't forget to free memory.

Fixes provided by Steve Greenland <stevegr@debian.org> and extended for
CVE-2019-9704.

Bug-Debian: https://bugs.debian.org/264320
Forwarded: no
Last-Update: 2019-03-23
Index: cron/compat.c
===================================================================
--- cron.orig/compat.c
+++ cron/compat.c
@@ -53,7 +53,10 @@ strdup(str)
 {
 	char	*temp;
 
-	temp = malloc(strlen(str) + 1);
+	if ((temp = malloc(strlen(str) + 1)) == NULL) {
+		errno = ENOMEM;
+		return NULL;
+	}
 	(void) strcpy(temp, str);
 	return temp;
 }
Index: cron/env.c
===================================================================
--- cron.orig/env.c
+++ cron/env.c
@@ -28,7 +28,8 @@ env_init()
 {
 	register char	**p = (char **) malloc(sizeof(char **));
 
-	p[0] = NULL;
+	if (p)
+		p[0] = NULL;
 	return (p);
 }
 
@@ -58,8 +59,18 @@ env_copy(envp)
 	for (count = 0;  envp[count] != NULL;  count++)
 		;
 	p = (char **) malloc((count+1) * sizeof(char *));  /* 1 for the NULL */
+	if (p == NULL) {
+		errno = ENOMEM;
+		return NULL;
+	}
 	for (i = 0;  i < count;  i++)
-		p[i] = strdup(envp[i]);
+		if ((p[i] = strdup(envp[i])) == NULL) {
+			while (--i >= 0)
+				(void) free(p[i]);
+			free(p);
+			errno = ENOMEM;
+			return NULL;
+		}
 	p[count] = NULL;
 	return (p);
 }
@@ -90,7 +101,11 @@ env_set(envp, envstr)
 		 * save our new one there, and return the existing array.
 		 */
 		free(envp[found]);
-		envp[found] = strdup(envstr);
+		if ((envp[found] = strdup(envstr)) == NULL) {
+			envp[found] = "";
+			errno = ENOMEM;
+			return NULL;
+		}
 		return (envp);
 	}
 
@@ -101,8 +116,15 @@ env_set(envp, envstr)
 	 */
 	p = (char **) realloc((void *) envp,
 			      (unsigned) ((count+1) * sizeof(char **)));
+	if (p == NULL) 	{
+		errno = ENOMEM;
+		return NULL;
+	}
 	p[count] = p[count-1];
-	p[count-1] = strdup(envstr);
+	if ((p[count-1] = strdup(envstr)) == NULL) {
+		errno = ENOMEM;
+		return NULL;
+	}
 	return (p);
 }
 
Index: cron/job.c
===================================================================
--- cron.orig/job.c
+++ cron/job.c
@@ -45,7 +45,8 @@ job_add(e, u)
 		if (j->e == e && j->u == u) { return; }
 
 	/* build a job queue element */
-	j = (job*)malloc(sizeof(job));
+	if ((j = (job*)malloc(sizeof(job))) == NULL)
+		return;
 	j->next = (job*) NULL;
 	j->e = e;
 	j->u = u;
Index: cron/misc.c
===================================================================
--- cron.orig/misc.c
+++ cron/misc.c
@@ -479,7 +479,12 @@ log_it(username, xpid, event, detail)
 		     + strlen(event)
 		     + strlen(detail)
 		     + MAX_TEMPSTR);
-
+	if (msg == NULL) {
+		/* damn, out of mem and we did not test that before... */
+		fprintf(stderr, "%s: Run OUT OF MEMORY while %s\n",
+		    ProgramName, __FUNCTION__);
+	    return;
+	}
 	if (LogFD < OK) {
 		LogFD = open(LOG_FILE, O_WRONLY|O_APPEND|O_CREAT, 0600);
 		if (LogFD < OK) {
@@ -624,7 +629,8 @@ mkprints(src, len)
 {
 	register char *dst = malloc(len*4 + 1);
 
-	mkprint(dst, src, len);
+	if (dst)
+		mkprint(dst, src, len);
 
 	return dst;
 }
Index: cron/user.c
===================================================================
--- cron.orig/user.c
+++ cron/user.c
@@ -52,7 +52,7 @@ load_user(crontab_fd, pw, name)
 	user	*u;
 	entry	*e;
 	int	status;
-	char	**envp;
+	char	**envp, **tenvp;
 
 	if (!(file = fdopen(crontab_fd, "r"))) {
 		perror("fdopen on crontab_fd in load_user");
@@ -63,14 +63,25 @@ load_user(crontab_fd, pw, name)
 
 	/* file is open.  build user entry, then read the crontab file.
 	 */
-	u = (user *) malloc(sizeof(user));
-	u->name = strdup(name);
+	if ((u = (user *) malloc(sizeof(user))) == NULL) {
+		errno = ENOMEM;
+		return NULL;
+	}
+	if ((u->name = strdup(name)) == NULL) {
+		free(u);
+		errno = ENOMEM;
+		return NULL;
+	}
 	u->crontab = NULL;
 
 	/* 
 	 * init environment.  this will be copied/augmented for each entry.
 	 */
-	envp = env_init();
+	if ((envp = env_init()) == NULL) {
+		free(u->name);
+		free(u);
+		return NULL;
+	}
 
 	/*
 	 * load the crontab
@@ -90,7 +101,13 @@ load_user(crontab_fd, pw, name)
 			}
 			break;
 		case TRUE:
-			envp = env_set(envp, envstr);
+			if ((tenvp = env_set(envp, envstr))) {
+				envp = tenvp;
+			} else {
+				free_user(u);
+				u = NULL;
+				goto done;
+			}
 			break;
 		}
 	}
Index: cron/entry.c
===================================================================
--- cron.orig/entry.c
+++ cron/entry.c
@@ -91,6 +91,7 @@ load_entry(file, error_func, pw, envp)
 	int	ch;
 	char	cmd[MAX_COMMAND];
 	char	envstr[MAX_ENVSTR];
+	char	**tenvp;
 
 	Debug(DPARS, ("load_entry()...about to eat comments\n"))
 
@@ -106,6 +107,10 @@ load_entry(file, error_func, pw, envp)
 	 */
 
 	e = (entry *) calloc(sizeof(entry), sizeof(char));
+	if (e == NULL) {
+		log_it("CRON", getpid(), "OOM", "Out of memory parsing crontab");
+		return NULL;
+	}
 
 	if (ch == '@') {
 		/* all of these should be flagged and load-limited; i.e.,
@@ -247,24 +252,52 @@ load_entry(file, error_func, pw, envp)
 	/* copy and fix up environment.  some variables are just defaults and
 	 * others are overrides.
 	 */
-	e->envp = env_copy(envp);
+	if ((e->envp = env_copy(envp)) == NULL) {
+		ecode = e_none;
+		goto eof;
+	}
 	if (!env_get("SHELL", e->envp)) {
 		sprintf(envstr, "SHELL=%s", _PATH_BSHELL);
-		e->envp = env_set(e->envp, envstr);
+		if ((tenvp = env_set(e->envp, envstr))) {
+			e->envp = tenvp;
+		} else {
+			ecode = e_none;
+			goto eof;
+		}
 	}
 	if (!env_get("HOME", e->envp)) {
 		sprintf(envstr, "HOME=%s", pw->pw_dir);
-		e->envp = env_set(e->envp, envstr);
+		if ((tenvp = env_set(e->envp, envstr))) {
+			e->envp = tenvp;
+		} else {
+			ecode = e_none;
+			goto eof;
+		}
 	}
 	if (!env_get("PATH", e->envp)) {
 		sprintf(envstr, "PATH=%s", _PATH_DEFPATH);
-		e->envp = env_set(e->envp, envstr);
+		if ((tenvp = env_set(e->envp, envstr))) {
+			e->envp = tenvp;
+		} else {
+			ecode = e_none;
+			goto eof;
+		}
 	}
 	sprintf(envstr, "%s=%s", "LOGNAME", pw->pw_name);
-	e->envp = env_set(e->envp, envstr);
+	if ((tenvp = env_set(e->envp, envstr))) {
+		e->envp = tenvp;
+	} else {
+		ecode = e_none;
+		goto eof;
+	}
 #if defined(BSD)
 	sprintf(envstr, "%s=%s", "USER", pw->pw_name);
-	e->envp = env_set(e->envp, envstr);
+	if ((tenvp = env_set(e->envp, envstr))) {
+		e->envp = tenvp;
+	} else {
+		ecode = e_none;
+		goto eof;
+	}
 #endif
 
 	Debug(DPARS, ("load_entry()...about to parse command\n"))
@@ -285,7 +318,10 @@ load_entry(file, error_func, pw, envp)
 
 	/* got the command in the 'cmd' string; save it in *e.
 	 */
-	e->cmd = strdup(cmd);
+	if ((e->cmd = strdup(cmd)) == NULL) {
+		ecode = e_none;
+		goto eof;
+	}
 
 	Debug(DPARS, ("load_entry()...returning successfully\n"))
 
@@ -294,6 +330,10 @@ load_entry(file, error_func, pw, envp)
 	return e;
 
  eof:
+	if (e->envp)
+		env_free(e->envp);
+	if (e->cmd)
+		free(e->cmd);
 	free(e);
 	if (ecode != e_none && error_func)
 		(*error_func)(ecodes[(int)ecode]);
Index: cron/crontab.c
===================================================================
--- cron.orig/crontab.c
+++ cron/crontab.c
@@ -503,6 +503,10 @@ replace_cmd() {
 	time_t	now = time(NULL);
 	char	**envp = env_init();
 
+	if (envp == NULL) {
+		fprintf(stderr, "%s: Cannot allocate memory.\n", ProgramName);
+		return (-2);
+	}
 	(void) sprintf(n, "tmp.%d", Pid);
 	(void) sprintf(tn, CRON_TAB(n));
 	if (!(tmp = fopen(tn, "w+"))) {