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

["B Wyatt (Updated) (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/TS-996?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

B Wyatt updated TS-996:
-----------------------

    Attachment: m_host.v3.patch

Attaching V3 which has no changes from V2 save that it has the header changes (which existed in the original patch but were erroneously missed in the V2 patch)

I have been running this on a small handful of deployments for a few months, no major issues have cropped up. 
                
> 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
>            Assignee: Leif Hedstrom
>             Fix For: 3.1.2
>
>         Attachments: m_host.V2.patch, m_host.patch, m_host.v3.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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