Date: Fri, 27 Sep 2002 12:34:21 -0400 From: "Dan Langille" <dan@langille.org> To: Matthew Seaman <m.seaman@infracaninophile.co.uk> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: sendmail: File descriptors missing on startup: stderr; Bad file descriptor Message-ID: <3D94504D.7219.709D8853@localhost> In-Reply-To: <20020927163141.GA16132@happy-idiot-talk.infracaninophi> References: <3D941EE0.5166.6FDC7551@localhost>
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On 27 Sep 2002 at 17:31, Matthew Seaman wrote: > On Fri, Sep 27, 2002 at 09:03:28AM -0400, Dan Langille wrote: > > I keep seeing this in /var/log/maillog but do not know the cause: > > > > sendmail[42390]: File descriptors missing on startup: stderr; Bad > > file descriptor > > > > I'm on FreeBSD 4.6-STABLE #0: Thu Sep 26 09:02:16 EDT 2002 with > > sendmail 8.12.5 > > > > Any ideas on cause/fix? > > What command line are you using to start sendmail? That error message > suggests that the stderr file descriptor, which sendmail inherits from > the shell where it is started, is bogus. The kernel will sanity check > the standard descriptors when starting up SUID or SGID processes, and > if any are closed, will open them up again on /dev/null. There was an > egregious security bug exploiting that situation going the rounds a > few months ago. See > ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-02%3A23.s > tdio.asc > > However, that was fixed before 4.6-RELEASE. Also I believe that it > was never possible to attack sendmail that way because the first thing > sendmail does when being started in daemon mode is to walk through > it's filedescriptor table and close them all down. The standard 0, 1, > 2 descriptors are then immediately re-opened onto /dev/null. That's > something that should be standard procedure for starting up any > daemonized process and it is built into the daemon(3) function. I'm sorry, I didn't mean for this message to go out. I've solved the problem by upgrading netsaint. Thank you for your reply. -- Dan Langille I'm looking for a computer job: http://www.freebsddiary.org/dan_langille.php To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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