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  • Patrick McHardy's avatar
    [NETFILTER]: SNMP NAT: fix memory corruption · f41d5bb1
    Patrick McHardy authored
    
    
    Fix memory corruption caused by snmp_trap_decode:
    
    - When snmp_trap_decode fails before the id and address are allocated,
      the pointers contain random memory, but are freed by the caller
      (snmp_parse_mangle).
    
    - When snmp_trap_decode fails after allocating just the ID, it tries
      to free both address and ID, but the address pointer still contains
      random memory. The caller frees both ID and random memory again.
    
    - When snmp_trap_decode fails after allocating both, it frees both,
      and the callers frees both again.
    
    The corruption can be triggered remotely when the ip_nat_snmp_basic
    module is loaded and traffic on port 161 or 162 is NATed.
    
    Found by multiple testcases of the trap-app and trap-enc groups of the
    PROTOS c06-snmpv1 testsuite.
    
    Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    f41d5bb1