Hello,
I have encountered a segment fault in the handle_subagent_response()
function. I am using net-snmp-5.2.1.2 on Linux.
[EMAIL PROTECTED]:~/derekli# uname -a
Linux probe-59 2.6.10_mvlcge401-pc_target-x86_pentium4-05 #1 SMP Thu Jul 6
17:50:28 BST 2006 i686 GNU/Linux
Core was generated by `/opt/feed/bin/probed 0 0 1'.
Program terminated with signal 11, Segmentation fault.
#0 0xb7b237b3 in handle_subagent_response () from /opt/feed/lib/libSNMP.so
(gdb) bt
#0 0xb7b237b3 in handle_subagent_response () from /opt/feed/lib/libSNMP.so
#1 0xb7ba101f in _sess_process_packet () from /opt/feed/lib/libSNMP.so
#2 0xb7ba1fbf in _sess_read () from /opt/feed/lib/libSNMP.so
#3 0xb7ba1ff7 in snmp_sess_read () from /opt/feed/lib/libSNMP.so
#4 0xb7ba12ba in snmp_read () from /opt/feed/lib/libSNMP.so
#5 0xb7b801e2 in snmp_synch_response_cb () from /opt/feed/lib/libSNMP.so
#6 0xb7b2eda8 in agentx_synch_response () from /opt/feed/lib/libSNMP.so
#7 0xb7b2ee84 in agentx_open_session () from /opt/feed/lib/libSNMP.so
#8 0xb7b24164 in subagent_open_master_session () from
/opt/feed/lib/libSNMP.so
#9 0xb7b24575 in agentx_reopen_session () from /opt/feed/lib/libSNMP.so
#10 0xb7b248eb in agentx_check_session () from /opt/feed/lib/libSNMP.so
#11 0xb7bb8b1d in run_alarms () from /opt/feed/lib/libSNMP.so
#12 0xb7b148cc in agent_check_and_process () from /opt/feed/lib/libSNMP.so
#13 0xb7b12c14 in SNMP::mainLoopCb () from /opt/feed/lib/libSNMP.so
#14 0xb7dae483 in MainLoopManager::handleCallbacks () from
/opt/feed/lib/libScheduler.so
#15 0xb7db3c68 in Scheduler::enterMainLoop () from
/opt/feed/lib/libScheduler.so
#16 0xb7e4df29 in Loader::enterMainLoop () from /opt/feed/lib/libLoader.so
---Type <return> to continue, or q <return> to quit---
#17 0xb7e4c168 in Loader::startTheMEB () from /opt/feed/lib/libLoader.so
#18 0xb7e4b655 in createLoader () from /opt/feed/lib/libLoader.so
#19 0x0804ab18 in ProbeD::start ()
#20 0x08049b87 in main ()
(gdb) info registers
eax 0xcf63f90 217464720
ecx 0x4a0 1184
edx 0xbc64280 197542528
ebx 0x0 0
esp 0xbfffd598 0xbfffd598
ebp 0xbfffd5c8 0xbfffd5c8
esi 0x0 0
edi 0xc748fb0 208965552
eip 0xb7b237b3 0xb7b237b3
eflags 0x10283 66179
cs 0x73 115
ss 0x7b 123
ds 0x7b 123
es 0x7b 123
fs 0x0 0
gs 0x33 51
(gdb) disassemble handle_subagent_response
0xb7b237a3 <handle_subagent_response+1031>: mov DWORD PTR [edi+4],0x12
0xb7b237aa <handle_subagent_response+1038>: mov edx,DWORD PTR [ebp-4]
0xb7b237ad <handle_subagent_response+1041>: mov eax,DWORD PTR [edx+4]
0xb7b237b0 <handle_subagent_response+1044>: add esp,0xfffffff8
0xb7b237b3 <handle_subagent_response+1047>: mov eax,DWORD PTR [eax]
0xb7b237b5 <handle_subagent_response+1049>: mov DWORD PTR [edi],eax
This corresponds to these lines in the function;
pdu->command = AGENTX_MSG_RESPONSE;
pdu->version = smagic->session->version;
It looks like the value of session is invalid.
(gdb) x /32w $eax
0xcf63f90: Cannot access memory at address 0xcf63f90
The calling function is _sess_process_packet().
handle_subagent_response() is called (as a callback) from here;
if (callback == NULL
|| callback(NETSNMP_CALLBACK_OP_RECEIVED_MESSAGE, sp,
pdu->reqid, pdu, magic) == 1) {
At that point, _sess_process_packet is iterating though the
netsnmp_request_list requests in the snmp_internal_sessions structure isp.
Looking further up the stack, agentx_check_session() calls
agentx_reopen_session(), which indicates that a ping has failed.
I suspected that the session_list isnt being updated correctly on a
reopen, leaving an invalid entry, but I cant see anything wrong. Can
anyone else spot what might be going wrong?
Also, how does snmp_sync_response_cb() work, when called by
agentx_send_ping()? I can't see now the timeout is set.
Cheers,
Derek
-------------------------------------------------------------------------
Take Surveys. Earn Cash. Influence the Future of IT
Join SourceForge.net's Techsay panel and you'll get the chance to share your
opinions on IT & business topics through brief surveys - and earn cash
http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV
_______________________________________________
Net-snmp-coders mailing list
Net-snmp-coders@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/net-snmp-coders
