Date: Wed, 5 Feb 1997 14:26:01 +0100 (MET) From: Jean-Luc.Richier@imag.fr To: FreeBSD-gnats-submit@freebsd.org Subject: kern/2667: Bug in bpfattach Message-ID: <199702051326.OAA00408@tuna.imag.fr> Resent-Message-ID: <199702051330.FAA14661@freefall.freebsd.org>
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>Number: 2667
>Category: kern
>Synopsis: bpfattach can hang the system
>Confidential: yes
>Severity: serious
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Class: change-request
>Submitter-Id: current-users
>Arrival-Date: Wed Feb 5 05:30:00 PST 1997
>Last-Modified:
>Originator: Jean-Luc Richier
>Organization:
Institut IMAg, Grenoble, France
>Release: FreeBSD 2.1.6-RELEASE i386
>Environment:
>Description:
While working on the IPv6 extensions for NetBSD and FreeBSD,
I discovered a problem with bpfattach behaviour.
If one tries to make extensions to NetBSD, this behaviour raise problems.
Therefore I suggest corrections to the base distribution code.
If the ifattach function is called while a bpf filter is open, the system
hangs.
>How-To-Repeat:
- Make a modfication in the system which allows to configure a new driver at
any time (In my case, it is a dynamic modification of the number of IPv6
tunnel drivers)
- open bpf filters, for example run ``rarpd -a''
- configure a new driver
- some seconds later, the system will hang
>Fix:
Add a static variable to test if it is the first call to bpfattach
*** sys/net/bpf.c.DIST Sat Jun 8 08:14:15 1996
--- sys/net/bpf.c Wed Feb 5 11:43:23 1997
***************
*** 1271,1276 ****
--- 1271,1277 ----
{
struct bpf_if *bp;
int i;
+ static int already = 0;
#if BSD < 199103
static struct bpf_if bpf_ifs[NBPFILTER];
static int bpfifno;
***************
*** 1303,1311 ****
/*
* Mark all the descriptors free if this hasn't been done.
*/
! if (!D_ISFREE(&bpf_dtab[0]))
for (i = 0; i < NBPFILTER; ++i)
D_MARKFREE(&bpf_dtab[i]);
if (bootverbose)
printf("bpf: %s%d attached\n", ifp->if_name, ifp->if_unit);
--- 1304,1314 ----
/*
* Mark all the descriptors free if this hasn't been done.
*/
! if(!already) {
! already = 1;
for (i = 0; i < NBPFILTER; ++i)
D_MARKFREE(&bpf_dtab[i]);
+ }
if (bootverbose)
printf("bpf: %s%d attached\n", ifp->if_name, ifp->if_unit);
>Audit-Trail:
>Unformatted:
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