Description of problem:
weird behaviour on the network caused nmbd to dump core.
DOS from DOS shouldn't be possible!

Version-Release number of selected component (if applicable):
samba-3.0.26a-0.fc7

How reproducible:
only seen once:

Oct  9 09:15:54 server2 nmbd[2172]: [2007/10/09 09:15:54, 0]
nmbd/nmbd_incomingdgrams.c:process_local_master_announce(309) 
Oct  9 09:15:54 server2 nmbd[2172]:   process_local_master_announce: Server XPWS
at IP 10.0.1.158 is announcing itself as a local master browser for workgrou
p DOMAIN and we think we are master. Forcing election. 
Oct  9 09:15:54 server2 nmbd[2172]: [2007/10/09 09:15:54, 0]
nmbd/nmbd_become_lmb.c:unbecome_local_master_success(149) 
Oct  9 09:15:54 server2 nmbd[2172]:   ***** 
Oct  9 09:15:54 server2 nmbd[2172]:    
Oct  9 09:15:54 server2 nmbd[2172]:   Samba name server SERVER has stopped being
a local master browser for workgroup DOMAIN on subnet 10.0.1.2 
Oct  9 09:15:54 server2 nmbd[2172]:    
Oct  9 09:15:54 server2 nmbd[2172]:   ***** 

[time goes, no other nmbd entries logged]

Oct  9 09:16:12 server2 nmbd[2172]: [2007/10/09 09:16:11, 0]
nmbd/nmbd_nameregister.c:register_name_response(130) 
Oct  9 09:16:12 server2 nmbd[2172]:   register_name_response: server at IP
10.0.1.146 rejected our name registration of DOMAIN<1d> IP 10.0.1.2 with error
code 6. 
Oct  9 09:16:12 server2 nmbd[2172]: [2007/10/09 09:16:12, 0]
nmbd/nmbd_become_lmb.c:become_local_master_fail2(417) 
Oct  9 09:16:12 server2 nmbd[2172]:   become_local_master_fail2: failed to
register name DOMAIN<1d> on subnet 10.0.1.2. Failed to become a local master
browser. 
Oct  9 09:16:12 server2 nmbd[2172]: [2007/10/09 09:16:12, 0]
nmbd/nmbd_become_lmb.c:become_local_master_fail2(417) 
Oct  9 09:16:12 server2 nmbd[2172]:   become_local_master_fail2: failed to
register name DOMAIN<1d> on subnet 10.0.1.2. Failed to become a local master
browser. 
Oct  9 09:16:12 server2 nmbd[2172]: [2007/10/09 09:16:12, 0]
nmbd/nmbd_namelistdb.c:standard_success_release(419) 
Oct  9 09:16:12 server2 nmbd[2172]:   standard_success_release: Name release for
name ^A^B__MSBROWSE__^B<01> IP 10.0.1.2 on subnet 10.0.1.2. Name was not found
 on subnet. 
Oct  9 09:16:12 server2 nmbd[2172]: [2007/10/09 09:16:12, 0]
nmbd/nmbd_namelistdb.c:standard_fail_register(305) 
Oct  9 09:16:12 server2 nmbd[2172]:   standard_fail_register: Failed to
register/refresh name DOMAIN<1d> on subnet 10.0.1.2 
Oct  9 09:16:12 server2 nmbd[2172]: [2007/10/09 09:16:12, 0]
lib/fault.c:fault_report(41) 
Oct  9 09:16:12 server2 nmbd[2172]:  
=============================================================== 
Oct  9 09:16:12 server2 nmbd[2172]: [2007/10/09 09:16:12, 0]
lib/fault.c:fault_report(42) 
Oct  9 09:16:12 server2 nmbd[2172]:   INTERNAL ERROR: Signal 11 in pid 2172
(3.0.26a-0.fc7) 
Oct  9 09:16:12 server2 nmbd[2172]:   Please read the Trouble-Shooting section
of the Samba3-HOWTO 
Oct  9 09:16:12 server2 nmbd[2172]: [2007/10/09 09:16:12, 0]
lib/fault.c:fault_report(44) 
Oct  9 09:16:12 server2 nmbd[2172]:    
Oct  9 09:16:12 server2 nmbd[2172]:   From:
http://www.samba.org/samba/docs/Samba3-HOWTO.pdf 
Oct  9 09:16:12 server2 nmbd[2172]: [2007/10/09 09:16:12, 0]
lib/fault.c:fault_report(45) 
Oct  9 09:16:12 server2 nmbd[2172]:  
=============================================================== 
Oct  9 09:16:12 server2 nmbd[2172]: [2007/10/09 09:16:12, 0]
lib/util.c:smb_panic(1654) 
Oct  9 09:16:12 server2 nmbd[2172]:   PANIC (pid 2172): internal error 
Oct  9 09:16:12 server2 nmbd[2172]: [2007/10/09 09:16:12, 0]
lib/util.c:log_stack_trace(1758) 
Oct  9 09:16:12 server2 nmbd[2172]:   BACKTRACE: 13 stack frames: 
Oct  9 09:16:12 server2 nmbd[2172]:    #0 nmbd(log_stack_trace+0x2d) [0x800ac65d] 
Oct  9 09:16:12 server2 nmbd[2172]:    #1 nmbd(smb_panic+0x5d) [0x800ac78d] 
Oct  9 09:16:12 server2 nmbd[2172]:    #2 nmbd [0x800971fa] 
Oct  9 09:16:12 server2 nmbd[2172]:    #3 [0x12d420] 
Oct  9 09:16:12 server2 nmbd[2172]:    #4 nmbd(remove_response_record+0x51)
[0x80035a71] 
Oct  9 09:16:12 server2 nmbd[2172]:    #5
nmbd(retransmit_or_expire_response_records+0x1b3) [0x8002ff13] 
Oct  9 09:16:12 server2 nmbd[2172]:    #6
nmbd(unbecome_local_master_browser+0x1be) [0x80023a2e] 
Oct  9 09:16:12 server2 nmbd[2172]:    #7 nmbd [0x80023bfb] 
Oct  9 09:16:12 server2 nmbd[2172]:    #8 nmbd [0x8002e1ce] 
Oct  9 09:16:12 server2 nmbd[2172]:    #9 nmbd(run_packet_queue+0x320) [0x80031410] 
Oct  9 09:16:12 server2 nmbd[2172]:    #10 nmbd(main+0x86b) [0x80021b5b] 
Oct  9 09:16:12 server2 nmbd[2172]:    #11
/lib/libc.so.6(__libc_start_main+0xe0) [0x2ddf70] 
Oct  9 09:16:12 server2 nmbd[2172]:    #12 nmbd [0x8001fef1] 
Oct  9 09:16:12 server2 nmbd[2172]: [2007/10/09 09:16:12, 0]
lib/fault.c:dump_core(181) 
Oct  9 09:16:12 server2 nmbd[2172]:   dumping core in /var/log/samba/cores/nmbd 
Oct  9 09:16:12 server2 nmbd[2172]: 

Note that this setup sees a lot of master negotiations going on, apparently
because XP workstations (not member of the domain but using the domain as
workgroup) runs a firewall that makes them deaf in master elections. As a
workaround I'm moving them to another domain where they can do whatever they
want to.


Essential (?) part of config:
[global]
        workgroup = DOMAIN
        server string = SERVER
        netbios name = SERVER
        interfaces = 10.0.1.2/24 lo eth1 eth1:2 192.168.1.10/24 
        security = user
        passdb backend = tdbsam
        domain master = yes 
        local master = yes
        os level = 33
        preferred master = yes
        wins support = yes

(names slightly edited)