Date: Thu, 21 Mar 2002 12:46:49 -0800 (PST) From: Jiu Zheng <jiu@stbernard.com> To: freebsd-gnats-submit@FreeBSD.org Subject: bin/36175: Vsnprintf causes memeory leak Message-ID: <200203212046.g2LKknv33411@freefall.freebsd.org>
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>Number: 36175
>Category: bin
>Synopsis: Vsnprintf causes memeory leak
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Thu Mar 21 12:50:02 PST 2002
>Closed-Date:
>Last-Modified:
>Originator: Jiu Zheng
>Release: 4.x
>Organization:
St Bernard Software
>Environment:
FreeBSD sunrise.rapid.stbernard.com 4.2-RELEASE FreeBSD 4.2-RELEASE #2: Fri Jan 19 09:29:10 PST 2001 jiu@sunrise.ipinc.com:/usr/src/sys/compile/SUNRISE i386
>Description:
*Each time* vsnprintf is called with str == NULL, 1K of memory is
allocted and never get freed. This can cause memory leak for certain
applications.
For example, in the recent Samba 3.0 alpha release, there is such a
line
len = vsnprintf(NULL, 0, fmt, ap);
used to calculate the length of the string. Then a serious memery leak
is caused in winbindd (a deamon as a part of samba package).
I noticed in revision 1.15 of vsnprintf (CVS) the author said
"revert freeing of memory that gets allocated when str == NULL
(this will be fixed in a better way)"
I am not sure the author really means to allocate 1M of memory
if the function is called in such a way 1000 times in a program.
I think this should get fix ASAP.
Thank you.
>How-To-Repeat:
Just compile and run the following; and see the prog size grows
#include <stdio.h>
#include <stdarg.h>
void do_print(char const *fmt, ...) {
int len;
va_list ap;
va_start(ap, fmt);
len = vsnprintf(NULL, 0, fmt, ap);
va_end(ap);
}
int main() {
while(1) do_print("bad\n");
}
>Fix:
The author, assar, must know
>Release-Note:
>Audit-Trail:
>Unformatted:
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