Fail early, fail hard.

etc/login.defs

@@ -143,7 +143,7 @@ HUSHLOGIN_FILE	.hushlogin
 # If defined, either a TZ environment parameter spec or the
 # fully-rooted pathname of a file containing such a spec.
 #
-#ENV_TZ		TZ=CST6CDT
+#ENV_TZ		TZ=UTC
 #ENV_TZ		/etc/tzname
 
 #

lib/getdef.c

@@ -559,11 +559,12 @@ static void def_load (void)
 	 * Go through all of the lines in the file.
 	 */
 	while (fgets_a(buf, fp) != NULL) {
+		if (stpsep(buf, "\n") == NULL) {
+			SYSLOG(LOG_CRIT, "%s: %s", def_fname, _("Non-text file."));
+			exit(EXIT_FAILURE);
+		}
 
-		/*
-		 * Trim trailing whitespace.
-		 */
-		stpcpy(stprspn(buf, " \t\n"), "");
+		stpcpy(stprspn(buf, " \t"), "");
 
 		/*
 		 * Break the line into two fields.

lib/hushed.c

@@ -76,7 +76,10 @@ bool hushed (const char *username)
 		return false;
 	}
 	for (found = false; !found && (fgets_a(buf, fp) != NULL);) {
-		stpsep(buf, "\n");
+		if (stpsep(buf, "\n") == NULL) {
+			fclose(fp);
+			return false;
+		}
 		found = streq(buf, pw->pw_shell) ||
 		        streq(buf, pw->pw_name);
 	}

lib/limits.c

@@ -363,9 +363,13 @@ static int setup_user_limits (const char *uname)
 	 * FIXME: a better (smarter) checking should be done
 	 */
 	while (fgets_a(buf, fil) != NULL) {
-		if (strprefix(buf, "#") || strprefix(buf, "\n")) {
-			continue;
+		if (stpsep(buf, "\n") == NULL) {
+			fclose(fil);
+			return 0;
 		}
+		if (strspn(buf, "#") || streq(buf, ""))
+			continue;
+
 		memzero_a(tempbuf);
 		/* a valid line should have a username, then spaces,
 		 * then limits

lib/port.c

@@ -145,11 +145,15 @@ getportent(void)
 		errno = saveerr;
 		return NULL;
 	}
+
+	if (stpsep(buf, "\n") == NULL) {
+		errno = EINVAL;
+		return NULL;
+	}
+
 	if (strprefix(buf, "#"))
 		goto next;
 
-	stpsep(buf, "\n");
-
 	if (strsep2arr_a(buf, ":", fields) == -1)
 		goto next;
 

lib/tz.c

@@ -1,57 +1,55 @@
-/*
- * SPDX-FileCopyrightText: 1991 - 1994, Julianne Frances Haugh
- * SPDX-FileCopyrightText: 1991 - 1994, Chip Rosenthal
- * SPDX-FileCopyrightText: 1996 - 1998, Marek Michałkiewicz
- * SPDX-FileCopyrightText: 2003 - 2005, Tomasz Kłoczko
- * SPDX-FileCopyrightText: 2007 - 2010, Nicolas François
- *
- * SPDX-License-Identifier: BSD-3-Clause
- */
+// SPDX-FileCopyrightText: 1991-1994, Julianne Frances Haugh
+// SPDX-FileCopyrightText: 1991-1994, Chip Rosenthal
+// SPDX-FileCopyrightText: 1996-1998, Marek Michałkiewicz
+// SPDX-FileCopyrightText: 2003-2005, Tomasz Kłoczko
+// SPDX-FileCopyrightText: 2007-2010, Nicolas François
+// SPDX-FileCopyrightText: 2026, Alejandro Colomar <alx@kernel.org>
+// SPDX-License-Identifier: BSD-3-Clause
+
 
 #include "config.h"
 
 #ifndef USE_PAM
 
-#ident "$Id$"
-
+#include <limits.h>
 #include <stdio.h>
-#include <string.h>
 
-#include "defines.h"
-#include "getdef.h"
 #include "io/fgets/fgets.h"
 #include "prototypes.h"
 #include "string/strtok/stpsep.h"
 
 
+#define DEFAULT_TZ  "TZ=UTC"
+
+
 /*
  * tz - return local timezone name
  *
  * tz() determines the name of the local timezone by reading the
- * contents of the file named by ``fname''.
+ * contents of the file named by 'path'.
  */
-/*@observer@*/const char *tz (const char *fname)
+/*@observer@*/
+const char *
+tz(const char *path)
 {
-	FILE *fp = NULL;
-	const char *result;
-	static char tzbuf[BUFSIZ];
-
-	fp = fopen (fname, "r");
-	if (   (NULL == fp)
-	    || (fgets_a(tzbuf, fp) == NULL)) {
-		result = "TZ=CST6CDT";
-	} else {
-		stpsep(tzbuf, "\n");
-		result = tzbuf;
-	}
-
-	if (NULL != fp) {
-		(void) fclose (fp);
-	}
-
-	return result;
+	FILE         *fp;
+	static char  buf[LINE_MAX + 1];
+
+	fp = fopen(path, "r");
+	if (fp == NULL)
+		return DEFAULT_TZ;
+
+	if (fgets_a(buf, fp) == NULL)
+		goto def;
+	if (stpsep(buf, "\n") == NULL)
+		goto def;
+
+	fclose(fp);
+	return buf;
+def:
+	fclose(fp);
+	return DEFAULT_TZ;
 }
 #else				/* !USE_PAM */
 extern int ISO_C_forbids_an_empty_translation_unit;
 #endif				/* !USE_PAM */
-

lib/user_busy.c

@@ -130,6 +130,9 @@ static int check_status (const char *name, uid_t uid, pid_t pid, pid_t tid)
 		return 0;
 	}
 	while (fgets_a(line, sfile) != NULL) {
+		if (stpsep(line, "\n") == NULL)
+			goto nontext;
+
 		if (strprefix(line, "Uid:\t")) {
 			unsigned long ruid, euid, suid;
 
@@ -158,6 +161,7 @@ static int check_status (const char *name, uid_t uid, pid_t pid, pid_t tid)
 			return 0;
 		}
 	}
+nontext:
 	(void) fclose (sfile);
 	return 0;
 }

man/login.defs.d/ENV_TZ.xml

@@ -11,14 +11,14 @@
       If set, it will be used to define the TZ environment variable when
       a user login. The value can be the name of a timezone preceded by
       <replaceable>TZ=</replaceable> (for example
-      <replaceable>TZ=CST6CDT</replaceable>), or the full path to the file
+      <replaceable>TZ=UTC</replaceable>), or the full path to the file
       containing the timezone specification (for example
       <filename>/etc/tzname</filename>).
     </para>
     <!-- TODO: it can in fact be used to set any other variable-->
     <para>
       If a full path is specified but the file does not exist or cannot be
-      read, the default is to use <replaceable>TZ=CST6CDT</replaceable>.
+      read, the default is to use <replaceable>TZ=UTC</replaceable>.
     </para>
   </listitem>
 </varlistentry>

src/chgpasswd.c

@@ -348,7 +348,6 @@ int main (int argc, char **argv)
 
 	const struct group *gr;
 	struct group newgr;
-	bool errors = false;
 	intmax_t line = 0;
 	struct option_flags  flags = {.chroot = false};
 	bool process_selinux;
@@ -387,10 +386,8 @@ int main (int argc, char **argv)
 	while (fgets_a(buf, stdin) != NULL) {
 		line++;
 		if (stpsep(buf, "\n") == NULL) {
-			fprintf (stderr, _("%s: line %jd: line too long\n"),
-			         Prog, line);
-			errors = true;
-			continue;
+			fprintf(stderr, "%s: %jd: %s\n", Prog, line, _("Non-text file."));
+			goto fail;
 		}
 
 		/*
@@ -408,8 +405,7 @@ int main (int argc, char **argv)
 			fprintf (stderr,
 			         _("%s: line %jd: missing new password\n"),
 			         Prog, line);
-			errors = true;
-			continue;
+			goto fail;
 		}
 		newpwd = cp;
 		if (   (!eflg)
@@ -452,8 +448,7 @@ int main (int argc, char **argv)
 			fprintf (stderr,
 			         _("%s: line %jd: group '%s' does not exist\n"), Prog,
 			         line, name);
-			errors = true;
-			continue;
+			goto fail;
 		}
 #ifdef SHADOWGRP
 		if (is_shadow_grp) {
@@ -512,8 +507,7 @@ int main (int argc, char **argv)
 				fprintf (stderr,
 				         _("%s: line %jd: failed to prepare the new %s entry '%s'\n"),
 				         Prog, line, sgr_dbname (), newsg.sg_namp);
-				errors = true;
-				continue;
+				goto fail;
 			}
 		}
 		if (   (NULL == sg)
@@ -524,30 +518,26 @@ int main (int argc, char **argv)
 				fprintf (stderr,
 				         _("%s: line %jd: failed to prepare the new %s entry '%s'\n"),
 				         Prog, line, gr_dbname (), newgr.gr_name);
-				errors = true;
-				continue;
+				goto fail;
 			}
 		}
 	}
 
+	close_files (&flags);
+
+	nscd_flush_cache ("group");
+	sssd_flush_cache (SSSD_DB_GROUP);
+
+	return (0);
+fail:
 	/*
 	 * Any detected errors will cause the entire set of changes to be
 	 * aborted. Unlocking the group file will cause all of the
 	 * changes to be ignored. Otherwise the file is closed, causing the
 	 * changes to be written out all at once, and then unlocked
 	 * afterwards.
 	 */
-	if (errors) {
-		fprintf (stderr,
-		         _("%s: error detected, changes ignored\n"), Prog);
-		fail_exit (1, process_selinux);
-	}
-
-	close_files (&flags);
-
-	nscd_flush_cache ("group");
-	sssd_flush_cache (SSSD_DB_GROUP);
-
-	return (0);
+	fprintf(stderr, "%s: %s\n", Prog, _("error detected, changes ignored\n"));
+	fail_exit(1, process_selinux);
 }