[lwip-devel] [bug #64685] snmp traps build failure (dangling pointer)

[Erik Ekman]

URL:
  <https://savannah.nongnu.org/bugs/?64685>

                 Summary: snmp traps build failure (dangling pointer)
                   Group: lwIP - A Lightweight TCP/IP stack
               Submitter: yarrick
               Submitted: Sun 17 Sep 2023 11:42:22 AM CEST
                Category: None
                Severity: 3 - Normal
              Item Group: None
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: None
            lwIP version: 2.1.3


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Follow-up Comments:


-------------------------------------------------------
Date: Sun 17 Sep 2023 11:42:22 AM CEST By: Erik Ekman <yarrick>
When trying to build the fuzzer, I got this failure. Seems like it correctly
detected where a pointer is given the address of a struct from the stack.

This has likely been broken since being added in patch #15072 in 2018.

../../src/apps/snmp/snmp_traps.c: In function
‘snmp_send_trap_or_notification_or_inform_generic’:
../../src/apps/snmp/snmp_traps.c:401:24: error: storing the address of local
variable ‘snmp_v2_special_varbinds’ in ‘*varbinds.prev’
[-Werror=dangling-pointer=]
  401 |         varbinds->prev = &snmp_v2_special_varbinds[1];
      |         ~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../src/apps/snmp/snmp_traps.c:356:23: note: ‘snmp_v2_special_varbinds’
declared here
  356 |   struct snmp_varbind snmp_v2_special_varbinds[] = {
      |                       ^~~~~~~~~~~~~~~~~~~~~~~~
../../src/apps/snmp/snmp_traps.c:347:176: note: ‘varbinds’ declared here
  347 | snmp_send_trap_or_notification_or_inform_generic(struct snmp_msg_trap
*trap_msg, const struct snmp_obj_id *eoid, s32_t generic_trap, s32_t
specific_trap, struct snmp_varbind *varbinds)
      |                                                                       
                                                                              
    ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~
cc1: all warnings being treated as errors








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