[xorg-bugzilla-noise] [Bug 399] New: executable code in data areas must be marked executable

[bugzilla-daemon at pdx.freedesktop.org]

http://pdx.freedesktop.org/cgi-bin/bugzilla/show_bug.cgi?id=399

           Summary: executable code in data areas must be marked executable
           Product: xorg
           Version: CVS_head
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Server/general
        AssignedTo: xorg-bugzilla-noise at freedesktop.org
        ReportedBy: jdennis at redhat.com


With a greater emphasis on security some OS's are not allowing processors to
execute code in data areas, the default behavior is to only allow code to
execute in text segments. Programs that perform runtime generation of code run
afoul of this restriction with the result their process is aborted by the OS.
Various parts of X, Mesa, and DRI generate executable code in data areas, some
of these have been fixed, but others have been missed. This patch addresses
these omisssions. The Mesa fixes may need to be propaged into their project (I
will open a Mesa bug and point it here).

With respect to this patch please make note of the following: 

Documentation can be found in the file mem.c, it explains various options,
choices, alternate implementations, and why the final solution was picked.

This problem is common to many software components, I don't think this patch is
the optimal solution as it tends to attack things piecemeal, in some cases just
duplicating the same code. It would be better to have a single memory allocator
for executable memory, but that is beyond the scope of an immediate short term
solution.



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