kern/77111: After pppd establishes connection, if "options MAC" is enabled in the kernel, kernel panic happens.

[Wojciech A. Koszek]

The following reply was made to PR kern/77111; it has been noted by GNATS.

From: "Wojciech A. Koszek" <dunstan at freebsd.czest.pl>
To: bug-followup at FreeBSD.org
Cc:  
Subject: Re: kern/77111: After pppd establishes connection, if "options MAC" is enabled in the kernel, kernel panic happens.
Date: Tue, 15 Feb 2005 00:32:24 +0000

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 Hello,
 I'm not able to test it in working environment right now, but attached patch
 should correct this problem. Needs testing. The problem is that
 mac_check_ifnet_transmit() needs to have packet header in passed mbuf. This
 function is called from: pppwrite() -- pppoutput() --
 mac_check_ifnet_transmit(). Attached patch should correct this problem.
 
 -- 
 * Wojciech A. Koszek && dunstan at FreeBSD.czest.pl
 
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 Content-Disposition: attachment; filename="diff.0.ppp_tty.c"
 
 Patch against FreeBSD 5.3-STABLE, kern.osreldate: 503102.
 
 diff -upr /usr/src/sys/net/ppp_tty.c src/sys/net/ppp_tty.c
 --- /usr/src/sys/net/ppp_tty.c	Sat Feb 12 09:36:38 2005
 +++ src/sys/net/ppp_tty.c	Tue Feb 15 00:29:38 2005
 @@ -396,6 +396,16 @@ pppwrite(tp, uio, flag)
  	    splx(s);
  	    return (ENOBUFS);
  	}
 +	/* 
 +	 * mbuf has to hold packet header in order to pass tests made by
 +	 * mac_check_ifnet_transmit() in pppoutput(), when MAC is present in
 +	 * the kernel.
 +	 */
 +	if (!(m->m_flags & M_PKTHDR)) {
 +		m_free(m0);
 +		splx(s);
 +		return (EIO);
 +	}
  	m->m_len = 0;
  	if (uio->uio_resid >= MCLBYTES / 2)
  	    MCLGET(m, M_DONTWAIT);
 
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