[Bug libc/11754] RFE: dlopen of ET_EXEC file

["jreiser at BitWagon dot com" <sourceware-bugzilla@sourceware.org>]

------- Additional Comments From jreiser at BitWagon dot com  2010-06-25 01:32 -------
My application is an auditor (checker/verifier) and the target application
already has been built by someone else, usually without -fPIE -pie.

> "The usual handling for ET_EXEC files uses MAP_FIXED, which will clobber any
existing mappings."
Yes.  However, instead of calling mmap(.p_vaddr,,,MAP_FIXED,,):  omit the
MAP_FIXED, then compare the return value with .p_vaddr.  If the two addresses
are equal, then the space was available and has been filled with the correct
contents.  (As demonstrated by the test case, that is essentially the main
effect of  calling dlopen on the original file but with .e_type=ET_DYN.)  If the
return value from mmap does not equal .p_vaddr, then the pages weren't available
for some reason, and you get to decide what to do.

-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=11754

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