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Posted to bugs@httpd.apache.org by bu...@apache.org on 2018/05/02 08:32:35 UTC

[Bug 62344] New: Failing variable interpolation and memory allocation failure in ProxyHTMLURLMap

https://bz.apache.org/bugzilla/show_bug.cgi?id=62344

            Bug ID: 62344
           Summary: Failing variable interpolation and memory allocation
                    failure in ProxyHTMLURLMap
           Product: Apache httpd-2
           Version: 2.4.33
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: mod_proxy_html
          Assignee: bugs@httpd.apache.org
          Reporter: ewald@mailbox.org
  Target Milestone: ---

Created attachment 35903
  --> https://bz.apache.org/bugzilla/attachment.cgi?id=35903&action=edit
Fix variable interpolation and memory allocation failure in ProxyHTMLURLMap

The attached file ProxyHTMLURLMap-memory-allocation-failure.patch fixes a
potential memory allocation failure in ProxyHTMLURLMap in conjunction with a
failed variable interpolation.

To reproduce, enable variable interpolation in ProxyHTMLURLMap and use a
pattern with a variable and the pipe symbol | after the variable. For example:

SetEnv env replaced
ProxyHTMLEnable On
ProxyHTMLInterp On
ProxyHTMLURLMap / /${env}_and_|/subfolder" V

The problem is that in mod_proxy_html.c, interpolate_var(), searching for |
isn't restricted to within the variable ${...}.

This leads to a wrong variable interpolation and, depending on your
environment, a memory allocation failure.

If you enable trace1 logging for mod_proxy_html you will see something like
this:

[...] mod_proxy_html.c(744): Interpolating env}_and_  =>  /subfolder"

The attached patch fixes this:

[...] mod_proxy_html.c(750): Interpolating env  =>  replaced

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[Bug 62344] Failing variable interpolation and memory allocation failure in ProxyHTMLURLMap

Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=62344

--- Comment #4 from Micha Lenk <mi...@lenk.info> ---
Awesome, thanks for proposing the backport.

Just a comment on the mentioned memory allocation failure: The reason is the
pointer arithmetic, which in the described error case results in a negative
length, which then seems to get casted to a very big positive number. If the
system is short on memory, it won't be able to provide the requested amount of
memory. That is at least how I understood what is happening in the error case.

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[Bug 62344] Failing variable interpolation and memory allocation failure in ProxyHTMLURLMap

Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=62344

nsg-apache-httpd-maintenance@sophos.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |nsg-apache-httpd-maintenanc
                   |                            |e@sophos.com

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[Bug 62344] Failing variable interpolation and memory allocation failure in ProxyHTMLURLMap

Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=62344

Christophe JAILLET <ch...@wanadoo.fr> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #5 from Christophe JAILLET <ch...@wanadoo.fr> ---
This have been backported in r1833840.

This is part of 2.4.34.

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[Bug 62344] Failing variable interpolation and memory allocation failure in ProxyHTMLURLMap

Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=62344

Yann Ylavic <yl...@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|PatchAvailable              |FixedInTrunk

--- Comment #1 from Yann Ylavic <yl...@gmail.com> ---
Thanks, committed to trunk in r1830746.

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[Bug 62344] Failing variable interpolation and memory allocation failure in ProxyHTMLURLMap

Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=62344

--- Comment #3 from Yann Ylavic <yl...@gmail.com> ---
Proposed in r1830776.

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[Bug 62344] Failing variable interpolation and memory allocation failure in ProxyHTMLURLMap

Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=62344

--- Comment #2 from Micha Lenk <mi...@lenk.info> ---
Yann, can you please propose this for backporting to 2.4.x?

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[Bug 62344] Failing variable interpolation and memory allocation failure in ProxyHTMLURLMap

Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=62344

Micha Lenk <mi...@lenk.info> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |PatchAvailable
                 CC|                            |micha@lenk.info

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