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Date: Mon, 29 Apr 2002 10:21:54 -0700 (PDT)
From: Mike Hibler <mike@cs.utah.edu>
To: freebsd-gnats-submit@FreeBSD.org
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Subject: kern/37573: kernel crashes when changing dummynet pipe characteristics
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>Number:         37573
>Category:       kern
>Synopsis:       kernel crashes when changing dummynet pipe characteristics
>Confidential:   no
>Severity:       serious
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Apr 29 10:30:01 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator:     Mike Hibler
>Release:        4.3, 4.5, current
>Organization:
University of Utah
>Environment:
>Description:
There is an obvious race in netinet/ip_dummynet.c:config_pipe().
Interrupts are not blocked when changing the params of an existing
pipe.  The specific crash observed:

... -> config_pipe -> set_fs_parms -> config_red

  malloc a new w_q_lookup table but take an interrupt before
  intializing it, interrupt handler does:

... -> dummynet_io -> red_drops

  red_drops dereferences the uninitialized (zeroed) w_q_lookup table

>How-To-Repeat:
Change the characteristics of an active pipe frequently.
     
>Fix:
In ip_dummynet.c:config_pipe(), in the not-a-new-pipe case, splimp() protect pipe/queue manipulations (primarily the call to set_fs_parms).

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

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