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Date: Sat, 8 Sep 2001 22:20:36 +0200 (CEST)
From: Christian Carstensen <cc@devcon.net>
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Subject: kern/30440: possible null pointer deref in bpfdetach()
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>Number:         30440
>Category:       kern
>Synopsis:       possible null pointer deref in bpfdetach()
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sat Sep 08 13:30:01 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator:     Christian Carstensen
>Release:        FreeBSD 5.0-CURRENT i386
>Organization:
>Environment:
System: FreeBSD albert.gate5.de 5.0-CURRENT FreeBSD 5.0-CURRENT #25: Thu Sep 6 04:20:50 CEST 2001 root@albert.gate5.de:/usr/src/sys/i386/compile/ALBERT i386

>Description:
in net/bpf.c, bpfdetach(), stuct bpf_if *bp is used in a for loop, that,
if not terminated by break before, leaves bp == NULL.
evaluating (bp->bif_ifp == NULL) two lines later will cause a NULL pointer
dereference, resulting in trap 12.

>How-To-Repeat:
just call bpfdetach(ifp) with any ifp that has no bpf interface attached.

>Fix:
RCS file: /usr/cvs/src/sys/net/bpf.c,v
retrieving revision 1.80
diff -r1.80 bpf.c
1267c1267
<       if (bp->bif_ifp == NULL) {
---
>       if (bp == NULL || bp->bif_ifp == NULL) {

>Release-Note:
>Audit-Trail:
>Unformatted:

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