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https://issues.apache.org/jira/browse/TS-996?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13132822#comment-13132822
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B Wyatt commented on TS-996:
----------------------------
I am auditioning a fast/dirty fix for this that cache's a MIMEField pointer
instead of the string pointer if the host comes from the MIMEHdr. For Hosts in
the URL it uses the m_cached_url's copy instead of a top level copy which
should be immune to heap changes.
Ideally, I think that code is up for a bit of cleaning but this will hopefully
suffice for now.
The patch is attached as m_host.patch
> 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
> Attachments: 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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