Merge lp:~gandelman-a/ubuntu/quantal/liblockfile/lp941968 into lp:ubuntu/quantal/liblockfile

[Adam Gandelman]

[James Page (james-page)]

review: Approve

[James Page (james-page)]

Uploaded to quantal - MP needs marking as merged.

=== modified file '.pc/applied-patches'
--- .pc/applied-patches	2012-06-13 21:28:38 +0000
+++ .pc/applied-patches	2013-06-24 18:31:42 +0000
@@ -1,1 +1,2 @@
 Makefile.in.patch
+fix-buffer-overflows.patch

=== added directory '.pc/fix-buffer-overflows.patch'
=== added file '.pc/fix-buffer-overflows.patch/.timestamp'
=== added file '.pc/fix-buffer-overflows.patch/lockfile.c'
--- .pc/fix-buffer-overflows.patch/lockfile.c	1970-01-01 00:00:00 +0000
+++ .pc/fix-buffer-overflows.patch/lockfile.c	2013-06-24 18:31:42 +0000
@@ -0,0 +1,542 @@
+/*
+ * lockfile.c 	Safely creates a lockfile, also over NFS.
+ *		This file also holds the implementation for
+ *		the Svr4 maillock functions.
+ *
+ * Version:	@(#)lockfile.c  1.06  04-Jun-2004  [e-mail]
+ *
+ *		Copyright (C) Miquel van Smoorenburg 1997,1998,1999,2004.
+ *
+ *		This library is free software; you can redistribute it and/or
+ *		modify it under the terms of the GNU Library General Public
+ *		License as published by the Free Software Foundation; either
+ *		version 2 of the License, or (at your option) any later version.
+ */
+
+#include "autoconf.h"
+
+#include <sys/types.h>
+#if HAVE_SYS_PARAM_H
+#include <sys/param.h>
+#endif
+#include <sys/stat.h>
+#include <sys/wait.h>
+#include <stdio.h>
+#include <string.h>
+#include <signal.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <time.h>
+#include <errno.h>
+#include <lockfile.h>
+#include <maillock.h>
+
+#ifdef HAVE_UTIME
+#include <utime.h>
+#endif
+
+#ifdef LIB
+static char *mlockfile;
+static int  islocked = 0;
+#endif
+
+#ifndef LIB
+extern int check_sleep(int);
+#endif
+
+#if !defined(LIB) || defined(MAILGROUP)
+/*
+ *	See if we can write to the directory.
+ *	Returns: -1 fail
+ *		  0 OK writable
+ */
+#ifdef LIB
+static
+#endif
+int eaccess_write(char *fn, gid_t gid, struct stat *st)
+{
+	struct stat	tmp;
+	uid_t		uid = geteuid();
+	gid_t		*aux;
+	int		n, i;
+
+	if (st == NULL) st = &tmp;
+
+	if (stat(fn, st) != 0)
+		return -1;
+	errno = EPERM;
+
+	if (uid == 0) return 0;
+
+	if (st->st_uid == uid)
+		return (st->st_mode & 0200) ? 0 : -1;
+
+	if (st->st_gid == gid)
+		return (st->st_mode & 0020) ? 0 : -1;
+
+	if ((n = getgroups(0, NULL)) > 0) {
+		aux = malloc(n * sizeof(gid_t));
+		if (aux && getgroups(n, aux) == 0) {
+			for (i = 0; i < n; i++)
+				if (st->st_gid == aux[i]) {
+					free(aux);
+					return (st->st_mode & 0020) ? 0 : -1;
+				}
+		}
+		free(aux);
+	}
+
+	return (st->st_mode & 0002) ? 0 : -1;
+}
+#endif
+
+#if defined(LIB) && defined(MAILGROUP)
+/*
+ *	Can we write to the directory of the lockfile ?
+ */
+static int need_extern(const char *file)
+{
+	gid_t		egid = getegid();
+	struct stat	st;
+	static gid_t	mailgid = -1;
+	char		*dir;
+	char		*p;
+	int             ret;
+
+	/*
+	 *	Find directory.
+	 */
+	if ((dir = (char *)malloc(strlen(file) + 1)) == NULL)
+		return L_ERROR;
+	strcpy(dir, file);
+	if ((p = strrchr(dir, '/')) != NULL)
+		*p = 0;
+	else
+		strcpy(dir, ".");
+	if (eaccess_write(dir, egid, NULL) >= 0) {
+		free(dir);
+		return 0;
+	}
+
+	/*
+	 *	See if accessible for group mail. We find out what
+	 *	"group mail" is by statting LOCKPROG, that saves us
+	 *	from having to call getgrgid() in a library.
+	 */
+	if (mailgid == (gid_t)-1) {
+		if (stat(LOCKPROG, &st) < 0 || !(st.st_mode & S_ISGID))
+			return 0;
+		mailgid = st.st_gid;
+	}
+	ret = eaccess_write(dir, mailgid, NULL) >= 0;
+	free (dir);
+	return ret;
+}
+
+/*
+ *	Call external program to do the actual locking.
+ */
+static int do_extern(char *opt, const char *lockfile, int retries, int flags)
+{
+	sigset_t	set, oldset;
+	char		buf[4];
+	pid_t		pid, n;
+	int		st;
+
+	/*
+	 *	Block SIGCHLD. The main program might have installed
+	 *	handlers we don't want to call.
+	 */
+	sigemptyset(&set);
+	sigaddset(&set, SIGCHLD);
+	sigprocmask(SIG_BLOCK, &set, &oldset);
+
+	/*
+	 *	Fork, execute locking program and wait.
+	 */
+	if ((pid = fork()) < 0)
+		return L_ERROR;
+	if (pid == 0) {
+		sprintf(buf, "%d", retries % 1000);
+		execl(LOCKPROG, LOCKPROG, opt, "-r", buf, "-q",
+			(flags & L_PID) ? "-p" : "-N", lockfile, NULL);
+		_exit(L_ERROR);
+	}
+
+	/*
+	 *	Wait for return status - do something appropriate
+	 *	if program died or returned L_ERROR.
+	 */
+	while ((n = waitpid(pid, &st, 0)) != pid)
+		if (n < 0 && errno != EINTR)
+			break;
+	if (!sigismember(&oldset, SIGCHLD))
+		sigprocmask(SIG_UNBLOCK, &set, NULL);
+	if (n < 0)
+		return L_ERROR;
+	if (!WIFEXITED(st) || WEXITSTATUS(st) == L_ERROR) {
+		errno = EINTR;
+		return L_ERROR;
+	}
+
+	return WEXITSTATUS(st);
+}
+
+#endif
+
+/*
+ *	Create a lockfile.
+ */
+#ifdef LIB
+static
+#endif
+int lockfile_create_save_tmplock(const char *lockfile,
+		char *tmplock, int tmplocksz, int retries, int flags)
+{
+	struct stat	st, st1;
+	char		sysname[256];
+	char		buf[8];
+	char		*p;
+	int		sleeptime = 0;
+	int		statfailed = 0;
+	int		fd;
+	int		i, e, len;
+	int		dontsleep = 1;
+	int		tries = retries + 1;
+
+#ifdef MAXPATHLEN
+	/*
+	 *	Safety measure.
+	 */
+	if (strlen(lockfile) + 32 > MAXPATHLEN) {
+		errno = ENAMETOOLONG;
+		return L_ERROR;
+	}
+#endif
+
+	if (strlen(lockfile) + 32 + 1 > tmplocksz) {
+		errno = EINVAL;
+		return L_ERROR;
+	}
+
+#if defined(LIB) && defined(MAILGROUP)
+	if (need_extern(lockfile))
+		return do_extern("-l", lockfile, retries, flags);
+#endif
+
+	/*
+	 *	Create a temp lockfile (hopefully unique) and write
+	 *	either our pid/ppid in it, or 0\0 for svr4 compatibility.
+	 */
+	if (gethostname(sysname, sizeof(sysname)) < 0)
+		return L_ERROR;
+	if ((p = strchr(sysname, '.')) != NULL)
+		*p = 0;
+	/* strcpy is safe: length-check above, limited at sprintf below */
+	strcpy(tmplock, lockfile);
+	if ((p = strrchr(tmplock, '/')) == NULL)
+		p = tmplock;
+	else
+		p++;
+	sprintf(p, ".lk%05d%x%s",
+		(int)getpid(), (int)time(NULL) & 15, sysname);
+	i = umask(022);
+	fd = open(tmplock, O_WRONLY|O_CREAT|O_EXCL, 0644);
+	e = errno;
+	umask(i);
+	if (fd < 0) {
+		tmplock[0] = 0;
+		errno = e;
+		return L_TMPLOCK;
+	}
+	if (flags & (L_PID | L_PPID)) {
+		sprintf(buf, "%d\n",
+			(flags & L_PID) ? (int)getpid() : (int)getppid());
+		p = buf;
+		len = strlen(buf);
+	} else {
+		p = "0\n";
+		len = 2;
+	}
+	i = write(fd, p, len);
+	e = errno;
+	if (close(fd) != 0) {
+		e = errno;
+		i = -1;
+	}
+	if (i != len) {
+		unlink(tmplock);
+		tmplock[0] = 0;
+		errno = i < 0 ? e : EAGAIN;
+		return L_TMPWRITE;
+	}
+
+	/*
+	 *	Now try to link the temporary lock to the lock.
+	 */
+	for (i = 0; i < tries && tries > 0; i++) {
+
+		if (!dontsleep) {
+			sleeptime += 5;
+			if (sleeptime > 60) sleeptime = 60;
+#ifdef LIB
+			sleep(sleeptime);
+#else
+			if ((e = check_sleep(sleeptime)) != 0) {
+				unlink(tmplock);
+				tmplock[0] = 0;
+				return e;
+			}
+#endif
+		}
+		dontsleep = 0;
+
+
+		/*
+		 *	Now lock by linking the tempfile to the lock.
+		 *
+		 *	KLUDGE: some people say the return code of
+		 *	link() over NFS can't be trusted.
+		 *	EXTRA FIX: the value of the nlink field
+		 *	can't be trusted (may be cached).
+		 */
+		(void)link(tmplock, lockfile);
+
+		if (lstat(tmplock, &st1) < 0) {
+			tmplock[0] = 0;
+			return L_ERROR; /* Can't happen */
+		}
+
+		if (lstat(lockfile, &st) < 0) {
+			if (statfailed++ > 5) {
+				/*
+				 *	Normally, this can't happen; either
+				 *	another process holds the lockfile or
+				 *	we do. So if this error pops up
+				 *	repeatedly, just exit...
+				 */
+				e = errno;
+				(void)unlink(tmplock);
+				tmplock[0] = 0;
+				errno = e;
+				return L_MAXTRYS;
+			}
+			continue;
+		}
+
+		/*
+		 *	See if we got the lock.
+		 */
+		if (st.st_rdev == st1.st_rdev &&
+		    st.st_ino  == st1.st_ino) {
+			(void)unlink(tmplock);
+			tmplock[0] = 0;
+			return L_SUCCESS;
+		}
+		statfailed = 0;
+
+		/*
+		 *	If there is a lockfile and it is invalid,
+		 *	remove the lockfile.
+		 */
+		if (lockfile_check(lockfile, flags) == -1) {
+			unlink(lockfile);
+			dontsleep = 1;
+			/*
+			 *	If the lockfile was invalid, then the first
+			 *	try wasn't valid either - make sure we
+			 *	try at least once more.
+			 */
+			if (tries == 1) tries++;
+		}
+
+	}
+	(void)unlink(tmplock);
+	tmplock[0] = 0;
+	errno = EAGAIN;
+	return L_MAXTRYS;
+}
+
+int lockfile_create(const char *lockfile, int retries, int flags)
+{
+	char *tmplock;
+	int l, r, e;
+
+	l = strlen(lockfile)+32+1;
+	if ((tmplock = (char *)malloc(l)) == NULL)
+		return L_ERROR;
+	tmplock[0] = 0;
+	r = lockfile_create_save_tmplock(lockfile,
+						tmplock, l, retries, flags);
+	e = errno;
+	free(tmplock);
+	errno = e;
+	return r;
+}
+
+/*
+ *	See if a valid lockfile is present.
+ *	Returns 0 if so, -1 if not.
+ */
+int lockfile_check(const char *lockfile, int flags)
+{
+	struct stat	st, st2;
+	char		buf[16];
+	time_t		now;
+	pid_t		pid;
+	int		fd, len, r;
+
+	if (stat(lockfile, &st) < 0)
+		return -1;
+
+	/*
+	 *	Get the contents and mtime of the lockfile.
+	 */
+	time(&now);
+	pid = 0;
+	if ((fd = open(lockfile, O_RDONLY)) >= 0) {
+		/*
+		 *	Try to use 'atime after read' as now, this is
+		 *	the time of the filesystem. Should not get
+		 *	confused by 'atime' or 'noatime' mount options.
+		 */
+		len = 0;
+		if (fstat(fd, &st) == 0 &&
+		    (len = read(fd, buf, sizeof(buf))) >= 0 &&
+		    fstat(fd, &st2) == 0 &&
+		    st.st_atime != st2.st_atime)
+			now = st.st_atime;
+		close(fd);
+		if (len > 0 && (flags & (L_PID|L_PPID))) {
+			buf[len] = 0;
+			pid = atoi(buf);
+		}
+	}
+
+	if (pid > 0) {
+		/*
+		 *	If we have a pid, see if the process
+		 *	owning the lockfile is still alive.
+		 */
+		r = kill(pid, 0);
+		if (r == 0 || errno == EPERM)
+			return 0;
+		if (r < 0 && errno == ESRCH)
+			return -1;
+		/* EINVAL - FALLTHRU */
+	}
+
+	/*
+	 *	Without a pid in the lockfile, the lock
+	 *	is valid if it is newer than 5 mins.
+	 */
+
+	if (now < st.st_mtime + 300)
+		return 0;
+
+	return -1;
+}
+
+/*
+ *	Remove a lock.
+ */
+int lockfile_remove(const char *lockfile)
+{
+#if defined(LIB) && defined(MAILGROUP)
+	if (need_extern(lockfile))
+		return do_extern("-u", lockfile, 0, 0);
+#endif
+	return (unlink(lockfile) < 0 && errno != ENOENT) ? -1 : 0;
+}
+
+/*
+ *	Touch a lock.
+ */
+int lockfile_touch(const char *lockfile)
+{
+#ifdef HAVE_UTIME
+	return utime(lockfile, NULL);
+#else
+	return utimes(lockfile, NULL);
+#endif
+}
+
+#ifdef LIB
+/*
+ *	Lock a mailfile. This looks a lot like the SVR4 function.
+ *	Arguments: lusername, retries.
+ */
+int maillock(const char *name, int retries)
+{
+	char		*p, *mail;
+	char		*newlock;
+	int		i, e;
+	int             len, newlen;
+
+	if (islocked) return 0;
+
+#ifdef MAXPATHLEN
+	if (strlen(name) + sizeof(MAILDIR) + 6 > MAXPATHLEN) {
+		errno = ENAMETOOLONG;
+		return L_NAMELEN;
+	}
+#endif
+
+	/*
+	 *	If $MAIL is for the same username as "name"
+	 *	then use $MAIL instead.
+	 */
+
+	len = strlen(name)+strlen(MAILDIR)+6;
+	mlockfile = (char *)malloc(len);
+	if (!mlockfile)
+		return L_ERROR;
+	sprintf(mlockfile, "%s%s.lock", MAILDIR, name);
+	if ((mail = getenv("MAIL")) != NULL) {
+		if ((p = strrchr(mail, '/')) != NULL)
+			p++;
+		else
+			p = mail;
+		if (strcmp(p, name) == 0) {
+			newlen = strlen(mail)+6;
+#ifdef MAXPATHLEN
+			if (newlen > MAXPATHLEN) {
+				errno = ENAMETOOLONG;
+				return L_NAMELEN;
+			}
+#endif
+			if (newlen > len) {
+				newlock = (char *)realloc (mlockfile, newlen);
+				if (newlock == NULL) {
+					e = errno;
+					free (mlockfile);
+					mlockfile = NULL;
+					errno = e;
+					return L_ERROR;
+				}
+				mlockfile = newlock;
+			}
+			sprintf(mlockfile, "%s.lock", mail);
+		}
+	}
+	i = lockfile_create(mlockfile, retries, 0);
+	if (i == 0) islocked = 1;
+
+	return i;
+}
+
+void mailunlock(void)
+{
+	if (!islocked) return;
+	lockfile_remove(mlockfile);
+	free (mlockfile);
+	islocked = 0;
+}
+
+void touchlock(void)
+{
+	lockfile_touch(mlockfile);
+}
+#endif
+

=== modified file 'debian/changelog'
--- debian/changelog	2012-06-13 21:28:38 +0000
+++ debian/changelog	2013-06-24 18:31:42 +0000
@@ -1,3 +1,12 @@
+liblockfile (1.09-4.1) quantal-proposed; urgency=low
+
+  * debian/patches/fix-buffer-overflows.patch: Fix buffer overflows when
+    building strings
+    - Protect against overflows caused by long hostnames (LP: #941968)
+    - Protect against overflows caused by large PID numbers (LP: #1011477)
+
+ -- Adam Gandelman <[e-mail]>  Thu, 20 Jun 2013 12:49:40 -0700
+
 liblockfile (1.09-4) unstable; urgency=low
 
   * Multiarch issues

=== added file 'debian/patches/fix-buffer-overflows.patch'
--- debian/patches/fix-buffer-overflows.patch	1970-01-01 00:00:00 +0000
+++ debian/patches/fix-buffer-overflows.patch	2013-06-24 18:31:42 +0000
@@ -0,0 +1,113 @@
+Description: Fix buffer overflows when building strings
+ The first occurs in lockfile_create_save_tmplock() when building the
+ filename for the temporary lock file. The p buffer may not be large enough to
+ hold large pid numbers or long hostnames. This issue is fixed by using
+ snprintf(), rather than sprintf(), and adding appropriate field widths to the
+ conversion string. Long hostnames will be truncated to fit in the remainder of
+ the buffer length.
+ .
+ The second occurs in lockfile_create_save_tmplock() when buf is not long
+ enough to store large pid numbers. This issue is fixed by using snprintf().
+ Also, the length of buf is increased to 40, which is enough to hold a 128 bit
+ signed int. This will be sufficient for holding pid values for quite some time
+ into the future.
+ .
+ Additionally, the sprintf() in do_extern() is changed to snprintf() for
+ general security hardening. An overflow of buf is not currently possible.
+Bug-Debian: http://bugs.debian.org/677225
+Bug-Ubuntu: https://launchpad.net/bugs/941968
+Bug-Ubuntu: https://launchpad.net/bugs/1011477
+Author: Tyler Hicks <[e-mail]>
+Index: liblockfile-1.09/lockfile.c
+===================================================================
+--- liblockfile-1.09.orig/lockfile.c	2013-01-09 10:54:49.948588615 -0800
++++ liblockfile-1.09/lockfile.c	2013-01-09 12:19:07.328708811 -0800
+@@ -158,7 +158,7 @@
+ 	if ((pid = fork()) < 0)
+ 		return L_ERROR;
+ 	if (pid == 0) {
+-		sprintf(buf, "%d", retries % 1000);
++		snprintf(buf, sizeof(buf), "%d", retries % 1000);
+ 		execl(LOCKPROG, LOCKPROG, opt, "-r", buf, "-q",
+ 			(flags & L_PID) ? "-p" : "-N", lockfile, NULL);
+ 		_exit(L_ERROR);
+@@ -185,6 +185,14 @@
+ 
+ #endif
+ 
++#define TMPLOCKSTR		".lk"
++#define TMPLOCKSTRSZ		strlen(TMPLOCKSTR)
++#define TMPLOCKPIDSZ		5
++#define TMPLOCKTIMESZ		1
++#define TMPLOCKSYSNAMESZ	23
++#define TMPLOCKFILENAMESZ	(TMPLOCKSTRSZ + TMPLOCKPIDSZ + \
++				 TMPLOCKTIMESZ + TMPLOCKSYSNAMESZ)
++
+ /*
+  *	Create a lockfile.
+  */
+@@ -196,7 +204,7 @@
+ {
+ 	struct stat	st, st1;
+ 	char		sysname[256];
+-	char		buf[8];
++	char		buf[40];
+ 	char		*p;
+ 	int		sleeptime = 0;
+ 	int		statfailed = 0;
+@@ -209,13 +217,13 @@
+ 	/*
+ 	 *	Safety measure.
+ 	 */
+-	if (strlen(lockfile) + 32 > MAXPATHLEN) {
++	if (strlen(lockfile) + TMPLOCKFILENAMESZ > MAXPATHLEN) {
+ 		errno = ENAMETOOLONG;
+ 		return L_ERROR;
+ 	}
+ #endif
+ 
+-	if (strlen(lockfile) + 32 + 1 > tmplocksz) {
++	if (strlen(lockfile) + TMPLOCKFILENAMESZ + 1 > tmplocksz) {
+ 		errno = EINVAL;
+ 		return L_ERROR;
+ 	}
+@@ -233,14 +241,16 @@
+ 		return L_ERROR;
+ 	if ((p = strchr(sysname, '.')) != NULL)
+ 		*p = 0;
+-	/* strcpy is safe: length-check above, limited at sprintf below */
++	/* strcpy is safe: length-check above, limited at snprintf below */
+ 	strcpy(tmplock, lockfile);
+ 	if ((p = strrchr(tmplock, '/')) == NULL)
+ 		p = tmplock;
+ 	else
+ 		p++;
+-	sprintf(p, ".lk%05d%x%s",
+-		(int)getpid(), (int)time(NULL) & 15, sysname);
++	snprintf(p, TMPLOCKFILENAMESZ, "%s%0*d%0*x%s", TMPLOCKSTR,
++		 TMPLOCKPIDSZ, (int)getpid(),
++		 TMPLOCKTIMESZ, (int)time(NULL) & 15,
++		 sysname);
+ 	i = umask(022);
+ 	fd = open(tmplock, O_WRONLY|O_CREAT|O_EXCL, 0644);
+ 	e = errno;
+@@ -251,8 +261,8 @@
+ 		return L_TMPLOCK;
+ 	}
+ 	if (flags & (L_PID | L_PPID)) {
+-		sprintf(buf, "%d\n",
+-			(flags & L_PID) ? (int)getpid() : (int)getppid());
++		snprintf(buf, sizeof(buf), "%d\n",
++			 (flags & L_PID) ? (int)getpid() : (int)getppid());
+ 		p = buf;
+ 		len = strlen(buf);
+ 	} else {
+@@ -363,7 +373,7 @@
+ 	char *tmplock;
+ 	int l, r, e;
+ 
+-	l = strlen(lockfile)+32+1;
++	l = strlen(lockfile)+TMPLOCKFILENAMESZ+1;
+ 	if ((tmplock = (char *)malloc(l)) == NULL)
+ 		return L_ERROR;
+ 	tmplock[0] = 0;

=== modified file 'debian/patches/series'
--- debian/patches/series	2012-06-13 21:28:38 +0000
+++ debian/patches/series	2013-06-24 18:31:42 +0000
@@ -1,1 +1,2 @@
 Makefile.in.patch
+fix-buffer-overflows.patch

=== modified file 'lockfile.c'
--- lockfile.c	2011-08-10 18:44:10 +0000
+++ lockfile.c	2013-06-24 18:31:42 +0000
@@ -158,7 +158,7 @@
 	if ((pid = fork()) < 0)
 		return L_ERROR;
 	if (pid == 0) {
-		sprintf(buf, "%d", retries % 1000);
+		snprintf(buf, sizeof(buf), "%d", retries % 1000);
 		execl(LOCKPROG, LOCKPROG, opt, "-r", buf, "-q",
 			(flags & L_PID) ? "-p" : "-N", lockfile, NULL);
 		_exit(L_ERROR);
@@ -185,6 +185,14 @@
 
 #endif
 
+#define TMPLOCKSTR		".lk"
+#define TMPLOCKSTRSZ		strlen(TMPLOCKSTR)
+#define TMPLOCKPIDSZ		5
+#define TMPLOCKTIMESZ		1
+#define TMPLOCKSYSNAMESZ	23
+#define TMPLOCKFILENAMESZ	(TMPLOCKSTRSZ + TMPLOCKPIDSZ + \
+				 TMPLOCKTIMESZ + TMPLOCKSYSNAMESZ)
+
 /*
  *	Create a lockfile.
  */
@@ -196,7 +204,7 @@
 {
 	struct stat	st, st1;
 	char		sysname[256];
-	char		buf[8];
+	char		buf[40];
 	char		*p;
 	int		sleeptime = 0;
 	int		statfailed = 0;
@@ -209,13 +217,13 @@
 	/*
 	 *	Safety measure.
 	 */
-	if (strlen(lockfile) + 32 > MAXPATHLEN) {
+	if (strlen(lockfile) + TMPLOCKFILENAMESZ > MAXPATHLEN) {
 		errno = ENAMETOOLONG;
 		return L_ERROR;
 	}
 #endif
 
-	if (strlen(lockfile) + 32 + 1 > tmplocksz) {
+	if (strlen(lockfile) + TMPLOCKFILENAMESZ + 1 > tmplocksz) {
 		errno = EINVAL;
 		return L_ERROR;
 	}
@@ -233,14 +241,16 @@
 		return L_ERROR;
 	if ((p = strchr(sysname, '.')) != NULL)
 		*p = 0;
-	/* strcpy is safe: length-check above, limited at sprintf below */
+	/* strcpy is safe: length-check above, limited at snprintf below */
 	strcpy(tmplock, lockfile);
 	if ((p = strrchr(tmplock, '/')) == NULL)
 		p = tmplock;
 	else
 		p++;
-	sprintf(p, ".lk%05d%x%s",
-		(int)getpid(), (int)time(NULL) & 15, sysname);
+	snprintf(p, TMPLOCKFILENAMESZ, "%s%0*d%0*x%s", TMPLOCKSTR,
+		 TMPLOCKPIDSZ, (int)getpid(),
+		 TMPLOCKTIMESZ, (int)time(NULL) & 15,
+		 sysname);
 	i = umask(022);
 	fd = open(tmplock, O_WRONLY|O_CREAT|O_EXCL, 0644);
 	e = errno;
@@ -251,8 +261,8 @@
 		return L_TMPLOCK;
 	}
 	if (flags & (L_PID | L_PPID)) {
-		sprintf(buf, "%d\n",
-			(flags & L_PID) ? (int)getpid() : (int)getppid());
+		snprintf(buf, sizeof(buf), "%d\n",
+			 (flags & L_PID) ? (int)getpid() : (int)getppid());
 		p = buf;
 		len = strlen(buf);
 	} else {
@@ -363,7 +373,7 @@
 	char *tmplock;
 	int l, r, e;
 
-	l = strlen(lockfile)+32+1;
+	l = strlen(lockfile)+TMPLOCKFILENAMESZ+1;
 	if ((tmplock = (char *)malloc(l)) == NULL)
 		return L_ERROR;
 	tmplock[0] = 0;