Handle a memory leak when contextName is used in the PDU. The memory … #78
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…for contextName is assigned to community and is hence lost. This is discussed further in issue net-snmp#58 along with a valgrind report.
bvanassche
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Mar 9, 2020
Fix a memory leak when contextName is used in the PDU. The memory for contextName is assigned to community and is hence lost. This patch fixes the following Valgrind complaint: at 0x4C29EA3: malloc (vg_replace_malloc.c:309) by 0x653F294: snmp_clone_mem (in /usr/lib64/libnetsnmp.so.31.0.2) by 0x653F3E7: ??? (in /usr/lib64/libnetsnmp.so.31.0.2) by 0x653F90D: snmp_clone_pdu (in /usr/lib64/libnetsnmp.so.31.0.2) by 0x60E3837: handle_agentx_packet (in /usr/lib64/libnetsnmpagent.so.31.0.2) by 0x6567ED0: ??? (in /usr/lib64/libnetsnmp.so.31.0.2) by 0x6568F40: _sess_read (in /usr/lib64/libnetsnmp.so.31.0.2) by 0x65698A8: snmp_sess_read2 (in /usr/lib64/libnetsnmp.so.31.0.2) by 0x65698FA: snmp_read2 (in /usr/lib64/libnetsnmp.so.31.0.2) by 0x656993B: snmp_read (in /usr/lib64/libnetsnmp.so.31.0.2) by 0x60DF30A: agent_check_and_process (in /usr/lib64/libnetsnmpagent.so.31.0.2) See also net-snmp#78. See also net-snmp#58. [ bvanassche: modified commit message and patch ]
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A slightly modified patch has been applied on the v5.8 and master branches. Thanks for the patch! |
LeSpocky
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Apr 13, 2020
Fix a memory leak when contextName is used in the PDU. The memory for contextName is assigned to community and is hence lost. This patch fixes the following Valgrind complaint: at 0x4C29EA3: malloc (vg_replace_malloc.c:309) by 0x653F294: snmp_clone_mem (in /usr/lib64/libnetsnmp.so.31.0.2) by 0x653F3E7: ??? (in /usr/lib64/libnetsnmp.so.31.0.2) by 0x653F90D: snmp_clone_pdu (in /usr/lib64/libnetsnmp.so.31.0.2) by 0x60E3837: handle_agentx_packet (in /usr/lib64/libnetsnmpagent.so.31.0.2) by 0x6567ED0: ??? (in /usr/lib64/libnetsnmp.so.31.0.2) by 0x6568F40: _sess_read (in /usr/lib64/libnetsnmp.so.31.0.2) by 0x65698A8: snmp_sess_read2 (in /usr/lib64/libnetsnmp.so.31.0.2) by 0x65698FA: snmp_read2 (in /usr/lib64/libnetsnmp.so.31.0.2) by 0x656993B: snmp_read (in /usr/lib64/libnetsnmp.so.31.0.2) by 0x60DF30A: agent_check_and_process (in /usr/lib64/libnetsnmpagent.so.31.0.2) See also net-snmp#78. See also net-snmp#58. [ bvanassche: modified commit message and patch ]
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We found that the internalPDU->contextName was assigned to the internalPDU->community resulting in losing the reference to the assigned memory of internalPDU->contextName. This memory is never free'ed when the internalPDU is deallocated. I tested the issue in 5.3, 5.8 and master branch. The issue does not happen if contextName is not used
Proposed fix:
contextNames memory should be freed before assignment to community, so that the memory is not lost.
This is discussed further in issue #58 along with a valgrind report.