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Posted to issues@guacamole.apache.org by "Mike Jumper (Jira)" <ji...@apache.org> on 2023/05/06 06:52:00 UTC

[jira] [Assigned] (GUACAMOLE-1784) guac_user instances must only be referenced from user callbacks

     [ https://issues.apache.org/jira/browse/GUACAMOLE-1784?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Mike Jumper reassigned GUACAMOLE-1784:
--------------------------------------

    Assignee: Mike Jumper

> guac_user instances must only be referenced from user callbacks
> ---------------------------------------------------------------
>
>                 Key: GUACAMOLE-1784
>                 URL: https://issues.apache.org/jira/browse/GUACAMOLE-1784
>             Project: Guacamole
>          Issue Type: Bug
>          Components: guacamole-server
>            Reporter: Mike Jumper
>            Assignee: Mike Jumper
>            Priority: Minor
>
> An instance of {{guac_user}} has a lifecycle that may result in that {{guac_user}} becoming invalid at any moment _except_ within the context of a callback directly related to that user. The {{guac_client_for_user()}} function exists to provide a mechanism for referencing a {{guac_user}} without a corresponding callback, but this call is missing in a few locations, resulting in potential segfaults.
> For example:
> {code:c}
> static void guac_rdp_audio_buffer_ack(guac_rdp_audio_buffer* audio_buffer,
>         const char* message, guac_protocol_status status) {
>     guac_user* user = audio_buffer->user;
>     guac_stream* stream = audio_buffer->stream;
>     ...
>     guac_protocol_send_ack(user->socket, stream, message, status);
>     ...
> }   
> {code}
> The above is incorrect because {{user->socket}} is being accessed outside a user-related callback and without using {{{}guac_client_for_user(){}}}. If the {{user}} turns out to not be valid, this will segfault.
> We should fix the above, look through the code for other references to {{guac_user}} outside a user-related callback, and fix those as well.



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