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

[Rusty Newton (JIRA)]

     [ https://issues.asterisk.org/jira/browse/ASTERISK-25021?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Rusty Newton updated ASTERISK-25021:
------------------------------------

    Description: 
After upgrading asterisk,, the daemon crashes on startup if the autoload=yes option iis not enabled in modules.conf's modules section.

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: 
[edit by Rusty - inline patch removed as per the guidelines, see comment on patch contribution process]

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.

  was:
After upgrading asterisk,, the daemon crashes on startup if the autoload=yes option iis not enabled in modules.conf's modules section.

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://cvsweb.netbsd.org/bsdweb.cgi/pkgsrc/comms/asterisk18/patches/patch-main_loader.c?rev=1.1]

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.


> 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 autoload=yes option iis not enabled in modules.conf's modules section.
> 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: 
> [edit by Rusty - inline patch removed as per the guidelines, see comment on patch contribution process]
> 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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