[jira] [Commented] (TS-996) HTTPHdr::m_host goes stale if HdrHeap::evacuate_from_str_heaps is called

["Leif Hedstrom (Commented) (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/TS-996?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13182313#comment-13182313 ] 

Leif Hedstrom commented on TS-996:
----------------------------------

I think the V2 patch is missing some changes (the header definitions for sure). Can you please update with a new patch, and I'll review it.

Thanks!
                
> HTTPHdr::m_host goes stale if HdrHeap::evacuate_from_str_heaps is called
> ------------------------------------------------------------------------
>
>                 Key: TS-996
>                 URL: https://issues.apache.org/jira/browse/TS-996
>             Project: Traffic Server
>          Issue Type: Bug
>          Components: HTTP, MIME
>    Affects Versions: 3.1.0
>            Reporter: B Wyatt
>             Fix For: 3.1.2
>
>         Attachments: m_host.V2.patch, m_host.patch
>
>
> class HTTPHdr stores a copy of the string pointer from either the URLimpl or the MIMEHdr for the host name in m_host.  In both cases, these strings can be moved to a new heap underneath the HTTPHdr.  When this happens, the process will, at best read stale memory and be fine and at worst read unmapped memory and segfault. 
> Currently, HdrHeap::evacuate_from_str_heaps is called to coalesce multiple heaps into a single heap.  When this happens it will directly access the low level objects via ::move_strings calls.  These objects do not posses the necessary information to inform parent objects about the change, nor does the HdrHeap directly inform interested parties.

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