[Bro-Dev] [JIRA] (BIT-1298) IP_Hdr pointer do not propagate from udp to child analyzers via DeliverPacket method causing a segfault

[Jon Siwek (JIRA)]

    [ https://bro-tracker.atlassian.net/browse/BIT-1298?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=19202#comment-19202 ] 

Jon Siwek commented on BIT-1298:
--------------------------------

I'm not easily reproducing this for NTP.  Can you give the stack trace and/or elaborate more on any code you've modified?

And the only place I'm seeing Analyzer::ForwardPacket explicitly propagate a null IP_Hdr* is in DNS over TCP (because it's reassembling a stream and may not have a single associated IP header).  But in that case, it's forwarding on to the analyzer for DNS over UDP (to re-use the same analysis logic), which doesn't make use of that pointer.   If you're writing code that relies on the current DNS analyzer, I think it's just going to have to anticipate the IP_Hdr* being null if the connection uses TCP.

> IP_Hdr pointer do not propagate from udp to child analyzers via DeliverPacket method causing a segfault
> -------------------------------------------------------------------------------------------------------
>
>                 Key: BIT-1298
>                 URL: https://bro-tracker.atlassian.net/browse/BIT-1298
>             Project: Bro Issue Tracker
>          Issue Type: Problem
>          Components: Bro
>    Affects Versions: 2.3
>         Environment: Debian
>            Reporter: Eric Asselin
>            Priority: High
>              Labels: analyzer
>         Attachments: core.zip
>
>
> From a child analyzer like NTP, the IP_Hdr pointer in the DeliverPacket method is empty and unusable causing a segmentation fault as soon as you try to access it.
> To recreate the bug, just add an "assert(ip)" inside the DeliverPacket method of a UDP child analyzer and the execution will fail (instead of the segmentation fault).



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