[asterisk-bugs] [JIRA] (ASTERISK-25021) Fix invalid pointer dereference on module load

[Emmanuel Dreyfus (JIRA)]

Emmanuel Dreyfus created ASTERISK-25021:
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             Summary: Fix invalid pointer dereference on module load
                 Key: ASTERISK-25021
                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-25021
             Project: Asterisk
          Issue Type: Bug
      Security Level: None
    Affects Versions: 1.8.32.3
            Reporter: Emmanuel Dreyfus


After upgrading asterisk,, the daemon crashes on startup if the [modules] autoload=yes is not enabled in modules.conf

This happens because of invalid pointer dereference during module loading. Here is the technical analysis:

If a module once failed to load with globally exposed symbols, the DSO is unloaded while the struct ast_module remains valid and referenced,  with just mod->lib being NULL.

If the module is later attempted to be loaded again, typically on a second attempt without globally exposed symbols, we get an unpleasant crash because mod->lib is used.

A fix is proposed here: 
http://ftp.espci.fr/shadow/manu/patch-main_loader.c

In this patch, we check mod->lib and if it is NULL, we call load_dynamic_module() again to reload the DSO.

Wa also add an additional test that mod->lib is not NULL to make sure code path using it will not be used if something still goes wrong.



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