http://www.slony.info/bugzilla/show_bug.cgi?id=55


paul cannon <pcannon+slonybugzilla at gmail.com> changed:

           What    |Removed                     |Added
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                 CC|                            |pcannon+slonybugzilla at gmail.
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--- Comment #1 from paul cannon <pcannon+slonybugzilla at gmail.com>  2009-09-15 13:13:02 ---
I've found one bug which would cause the symptoms you describe, although there
may be others :). Present in 1.2.15 and 1.2.16, at least.

The problem should manifest itself when an overly long line is printed to the
log (so it doesn't happen when the log level is low). Here's the case that was
causing my slon to segfault; it's in sync_event() in remote_worker.c:

            slon_log(SLON_DEBUG4, " ssy_action_list value: %s\n",
                     ssy_action_list);

ssy_action_list in this case was over 135000 characters. When this got into
slon_log and that function found that its buffer was not big enough, it tried
to resize the buffer and call vsnprintf() again, but /it reused the va_arg/,
which is not allowed.

Here is one possible approach to fixing the problem:

--- old_misc.c  2009-09-15 13:57:29.000000000 -0600
+++ misc.c      2009-09-15 14:11:10.000000000 -0600
@@ -172,7 +172,10 @@

        off = strlen(outbuf);

-       while (vsnprintf(&outbuf[off], outsize - off, fmt, ap) >= outsize -
off)
+       va_list apcopy;
+       va_copy(apcopy, ap);
+
+       while (vsnprintf(&outbuf[off], outsize - off, fmt, apcopy) >= outsize -
off)
        {
                outsize *= 2;
                outbuf = realloc(outbuf, outsize);
@@ -181,7 +184,12 @@
                        perror("slon_log: realloc()");
                        slon_retry();
                }
+               va_end(apcopy);
+               va_copy(apcopy, ap);
        }
+
+       va_end(apcopy);
+
 #ifdef HAVE_SYSLOG
        if (Use_syslog >= 1)
        {


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