Date: Wed, 18 Feb 2004 15:07:29 +0000 From: Cian Synnott <cian.synnott@eircom.net> To: FreeBSD-gnats-submit@FreeBSD.org Cc: cirt@eircom.net Subject: misc/63020: 'utsname' structure field 'nodename' is too short Message-ID: <20040218150729.GA79940@hardy.cirt.eircom.net> Resent-Message-ID: <200402181520.i1IFKFWj062607@freefall.freebsd.org>
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>Number: 63020
>Category: misc
>Synopsis: 'utsname' structure field 'nodename' is too short
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Wed Feb 18 07:20:14 PST 2004
>Closed-Date:
>Last-Modified:
>Originator: Cian Synnott
>Release: FreeBSD 4.9-STABLE i386
>Organization:
eircom.net Computer Incident Response Team
>Environment:
System: FreeBSD hardy.cirt.eircom.net 4.9-STABLE FreeBSD 4.9-STABLE #2: Fri Dec 19 14:38:17 GMT 2003 root@hardy.cirt.eircom.net:/usr/obj/usr/src/sys/HARDY i386
>Description:
The utsname structure defined in the sys/utsname.h has a maximum of
32 characters on all fields, including the 'nodename' - the network
name of the machine. This could reasonably be expected by a
programmer using the uname() call to be MAXHOSTNAMELEN in length.
However, long hostnames returned from the wrapped sysctl() are
truncated.
>How-To-Repeat:
Compile up something like this:
#include <stdio.h>
#include <sys/utsname.h>
int main()
{
struct utsname buf;
uname (&buf);
printf ("nodename: %s\n", buf.nodename);
return 0;
}
Then set your hostname to, say
verylongnameindeed.subdomain.domain.tld
and run the code. Compare output with that of '/usr/bin/uname', which
directly calls sysctl().
>Fix:
Have your program use gethostname() rather than uname() to workaround.
I expect a proper fix would be alter the utsname structure and uname()
to use proper lengths on structure fields.
>Release-Note:
>Audit-Trail:
>Unformatted:
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