[Bug 198385] syslogd seems to leak memory under certain circumstances
bugzilla-noreply at freebsd.org
bugzilla-noreply at freebsd.org
Sat Mar 7 11:46:40 UTC 2015
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=198385
Sreeram <sreeramabs at yahoo.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |sreeramabs at yahoo.com
--- Comment #1 from Sreeram <sreeramabs at yahoo.com> ---
The syslogd daemon seems to be leaking few bytes of memory when modifications
are done to the /etc/syslog.conf when it has entries to forward the syslog
messages to a remote-host, and
making syslogd read the new conf by signalling it with a SIGHUP.
Consider the following entries in /etc/syslog.conf
# $FreeBSD: releng/10.1/etc/syslog.conf 260519 2014-01-10 17:56:23Z asomers $
#
# Spaces ARE valid field separators in this file. However,
# other *nix-like systems still insist on using tabs as field
# separators. If you are sharing this file between systems, you
# may want to use only tabs as field separators here.
# Consult the syslog.conf(5) manpage.
*.err;kern.warning;auth.notice;mail.crit /dev/console
*.notice;authpriv.none;kern.debug;lpr.info;mail.crit;news.err
/var/log/messages
security.* /var/log/security
auth.info;authpriv.info /var/log/auth.log
mail.info /var/log/maillog
lpr.info /var/log/lpd-errs
ftp.info /var/log/xferlog
cron.* /var/log/cron
!-devd
*.=debug /var/log/debug.log
*.emerg *
# uncomment this to log all writes to /dev/console to /var/log/console.log
# touch /var/log/console.log and chmod it to mode 600 before it will work
#console.info /var/log/console.log
# uncomment this to enable logging of all log messages to /var/log/all.log
# touch /var/log/all.log and chmod it to mode 600 before it will work
#*.* /var/log/all.log
# uncomment this to enable logging to a remote loghost named loghost
#*.* @loghost
*.info @192.168.1.40
*.info @192.168.1.41
*.info @192.168.1.42
*.info @192.168.1.43
Now, the last three lines above are replaced with a line with different host,
So, the file (at those lines) looks like this:
*.info @192.168.1.40
*.info @192.168.1.51 << Two lines
removed
Now, I issue the 'kill -HUP <syslogd-pid>'
This would re-read this conf file, by first flushing out the current entries.
During this situation, the syslogd seems to be leaking few bytes of memory.
This is because, whenever syslogd reads the conf-file, and finds an entry for
remote-host, it issues a 'getaddrinfo' to get the name resolution for that
entry. getaddrinfo() will internally allocated memory for linked-list of
addresses related to that host, and will return the same. The caller is
supposed to free that memory by issuing freeaddrinfo() once his task is done.
The portion of code where getaddrinfo() is called in syslogd.c file of
FreeBSD-10.1 is:
1776
1777 /*
1778 * Crack a configuration file line
1779 */
1780 static void
1781 cfline(const char *line, struct filed *f, const char *prog, const char
*host)
1782 {
1783 struct addrinfo hints, *res;
1784 int error, i, pri, syncfile;
1785 const char *p, *q;
1786 char *bp;
...
...
1939
1940 switch (*p) {
1941 case '@':
1942 {
1943 char *tp;
1944 char endkey = ':';
...
...
1974 memset(&hints, 0, sizeof(hints));
1975 hints.ai_family = family;
1976 hints.ai_socktype = SOCK_DGRAM;
1977 error = getaddrinfo(f->f_un.f_forw.f_hname,
1978 p ? p : "syslog", &hints, &res);
1979 if (error) {
1980 logerror(gai_strerror(error));
1981 break;
1982 }
1983 f->f_un.f_forw.f_addr = res;
1984 f->f_type = F_FORW;
1985 break;
The address is collected and set ready for remote-logging the syslog messages.
Now, when changes are done to syslog.conf file, and SIGHUP issued, the init()
function gets called, and in this function, arrangements to free up this memory
returned by getaddrinfo() is not made.
The init() function looks like this:
1533
1534 /*
1535 * INIT -- Initialize syslogd from configuration table
1536 */
1537 static void
1538 init(int signo)
1539 {
1540 int i;
1541 FILE *cf;
1542 struct filed *f, *next, **nextp;
1543 char *p;
1544 char cline[LINE_MAX];
...
...
1577 switch (f->f_type) {
1578 case F_FILE:
1579 case F_FORW: <<<<<<< No arrangements to
call freeaddrinfo()
1588 case F_CONSOLE:
1581 case F_TTY:
1582 (void)close(f->f_file);
1583 break;
1584 case F_PIPE:
1585 if (f->f_un.f_pipe.f_pid > 0) {
1586 (void)close(f->f_file);
1587 deadq_enter(f->f_un.f_pipe.f_pid,
1588 f->f_un.f_pipe.f_pname);
1589 }
1590 f->f_un.f_pipe.f_pid = 0;
1591 break;
1592 }
This results in a memory leak.
Although this could be of few bytes, it would be nice to fix this, as the fix
is simple.
I have made the changes to syslogd.c (in my FreeBSD box) to fix this issue.
The changes look like this:
1577 switch (f->f_type) {
1578 case F_FILE:
1579 case F_FORW:
1580 if (f->f_un.f_forw.f_addr) { <<<
1581 freeaddrinfo(f->f_un.f_forw.f_addr);
<<< Call freeaddrinfo
1583 } <<<
1584 /* fall through */ <<<
1585 case F_CONSOLE:
1586 case F_TTY:
1587 (void)close(f->f_file);
1588 break;
1589 case F_PIPE:
1590 if (f->f_un.f_pipe.f_pid > 0) {
1591 (void)close(f->f_file);
1592 deadq_enter(f->f_un.f_pipe.f_pid,
1593 f->f_un.f_pipe.f_pname);
1594 }
1595 f->f_un.f_pipe.f_pid = 0;
1596 break;
1597 }
Request: I would like to take up this task of fixing this issue.
I have never contributed to FreeBSD-code before this, and this
is a great opportunity for me to fix this and contribute. But,
I request you to kindly suggest me the steps followed by other
developers in FreeBSD for fixing BUGs.
Please inform.
Regards,
Sreeram
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